Switch docs to MKDocs (#602)

Fixes #601. Merged in 6f87b32 from the md3 branch and did a lot of cleanup.

Changes include:

* Removed old docs build tool, templates, etc.

* Added MkDocs config file, etc.

* filename.txt => filename.md

* pythonhost.org/Markdown => Python-Markdown.github.io

* Markdown lint and other cleanup.

* Automate pages deployment in makefile with `mkdocs gh-deploy`

    Assumes a git remote is set up named "pages". Do

        git remote add pages https://github.com/Python-Markdown/Python-Markdown.github.io.git

    ... before running `make deploy` the first time.

1 files changed, 0 insertions, 187 deletions

diff --git a/docs/release-2.5.txt b/docs/release-2.5.txt
deleted file mode 100644
index 7cde02f..0000000
--- a/docs/release-2.5.txt
+++ /dev/null
@@ -1,187 +0,0 @@
-title:      Release Notes for v2.5
-prev_title: Release Notes for v2.6
-prev_url:   release-2.6.html
-next_title: Release Notes for v2.4
-next_url:   release-2.4.html
-
-Python-Markdown 2.5 Release Notes
-=================================
-
-We are pleased to release Python-Markdown 2.5 which adds a few new features
-and fixes various bugs. See the list of changes below for details.
-
-Python-Markdown version 2.5 supports Python versions 2.7, 3.2, 3.3, and 3.4.
-
-Backwards-incompatible Changes
-------------------------------
-
-* Python-Markdown no longer supports Python version 2.6. You must be using Python 
-  versions 2.7, 3.2, 3.3, or 3.4.
-
-[importlib]: https://pypi.python.org/pypi/importlib
-
-* The `force_linenos` configuration key on the [CodeHilite Extension] has been **deprecated**
-  and will raise a `KeyError` if provided. In the previous release (2.4), it was 
-  issuing a `DeprecationWarning`. The [`linenums`][linenums] keyword should be used 
-  instead, which provides more control of the output.
-
-[CodeHilite Extension]: extensions/code_hilite.html
-[linenums]: extensions/code_hilite.html#usage
-
-* Both `safe_mode` and the associated `html_replacement_text` keywords will be deprecated 
-  in version 2.6 and will raise a **`PendingDeprecationWarning`** in 2.5. The so-called
-  "safe mode" was never actually "safe" which has resulted in many people having a false 
-  sense of security when using it. As an alternative, the developers of Python-Markdown 
-  recommend that any untrusted content be passed through an HTML sanitizer (like [Bleach])
-  after being converted to HTML by markdown.
-
-    If your code previously looked like this:
-
-	    html = markdown.markdown(text, same_mode=True)
-
-	Then it is recommended that you change your code to read something like this:
-
-	    import bleach
-        html = bleach.clean(markdown.markdown(text))
-
-	If you are not interested in sanitizing untrusted text, but simply desire to escape
-	raw HTML, then that can be accomplished through an extension which removes HTML parsing:
-
-		from markdown.extensions import Extension
-
-		class EscapeHtml(Extension):
-			def extendMarkdown(self, md, md_globals):
-				del md.preprocessors['html_block']
-				del md.inlinePatterns['html']
-
-		html = markdown.markdown(text, extensions=[EscapeHtml()])
-
-	As the HTML would not be parsed with the above Extension, then the serializer will
-	escape the raw HTML, which is exactly what happens now when `safe_mode="escape"`.
-
-[Bleach]: https://bleach.readthedocs.io/
-
-* Positional arguments on the `markdown.Markdown()` are pending deprecation as are
-  all except the `text` argument on the `markdown.markdown()` wrapper function.
-  Only keyword arguments should be used. For example, if your code previously
-  looked like this:
-
-         html = markdown.markdown(text, ['extra'])
-    
-	Then it is recommended that you change it to read something like this:
-
-	    html = markdown.markdown(text, extensions=['extra'])
-
-	!!! Note
-	    This change is being made as a result of deprecating `"safe_mode"` as the 
-		`safe_mode` argument was one of the positional arguments. When that argument 
-		is removed, the two arguments following it will no longer be at the correct 
-		position. It is recommended that you always use keywords when they are supported
-		for this reason.
-
-* In previous versions of Python-Markdown, the built-in extensions received
-  special status and did not require the full path to be provided. Additionally,
-  third party extensions whose name started with `"mdx_"` received the same 
-  special treatment. This behavior will be deprecated in version 2.6 and will
-  raise a **`PendingDeprecationWarning`** in 2.5. Ensure that you always use the full 
-  path to your extensions. For example, if you previously did the following:
-
-        markdown.markdown(text, extensions=['extra'])
-
-    You should change your code to the following:
-
-	    markdown.markdown(text, extensions=['markdown.extensions.extra'])
-
-    The same applies to the command line:
-
-        $ python -m markdown -x markdown.extensions.extra input.txt
-
-    See the [documentation](reference.html#extensions) for a full explanation
-    of the current behavior.
-
-* The previously documented method of appending the extension configuration as 
-  a string to the extension name will be deprecated in Python-Markdown 
-  version 2.6 and will raise a **`PendingDeprecationWarning`** in 2.5. The 
-  [`extension_configs`](reference.html#extension_configs) keyword should 
-  be used instead. See the [documentation](reference.html#extension-configs) 
-  for a full explanation of the current behavior.
-
-What's New in Python-Markdown 2.5
----------------------------------
-
-*   The [Smarty Extension] has had a number of additional configuration settings
-    added, which allows one to define their own substitutions to better support
-    languages other than English. Thanks to [Martin Altmayer] for implementing this 
-	feature.
-
-[Smarty Extension]: extensions/smarty.html
-[Martin Altmayer]:https://github.com/MartinAltmayer
-
-*   Named Extensions (strings passed to the [`extensions`][ex] keyword of 
-    `markdown.Markdown`) can now point to any module and/or Class on your PYTHONPATH. 
-	While dot notation was previously supported, a module could not be at the root of 
-	your PYTHONPATH. The name had to contain at least one dot (requiring it to be a 
-	sub-module). This restriction no longer exists. 
-
-	Additionally, a Class may be specified in the name. The class must be at the end of 
-	the name (which uses dot notation from PYTHONPATH) and be separated by a colon from 
-	the module. 
-
-	Therefore, if you were to import the class like this:
-	
-		from path.to.module import SomeExtensionClass
-
-	Then the named extension would comprise this string:
-
-		"path.to.module:SomeExtensionClass"
-	
-	This allows multiple extensions to be implemented within the same module and still 
-	accessible when the user is not able to import the extension directly (perhaps from 
-	a template filter or the command line).
-
-	This also means that extension modules are no longer required to include the 
-	`makeExtension`	function which returns an instance of the extension class. However, 
-	if the user does not specify the class name (she only provides `"path.to.module"`)
-	the extension will fail to load without the `makeExtension` function included in
-	the module. Extension authors will want to document carefully what is required to
-	load their extensions.
-
-[ex]: reference.html#extensions
-
-*   The Extension Configuration code has been refactored to make it a little easier 
-    for extension authors to work with configuration settings. As a result, the 
-    [`extension_configs`][ec] keyword now accepts a dictionary rather than requiring 
-    a list of tuples. A list of tuples is still supported so no one needs to change 
-    their existing code. This should also simplify the learning curve for new users.
-
-	Extension authors are encouraged to review the new methods available on the 
-	`markdown.extnesions.Extension` class for handling configuration and adjust their
-	code going forward. The included extensions provide a model for best practices.
-	See the [API] documentation for a full explanation.
-
-[ec]: reference.html#extension_configs
-[API]: extensions/api.html#configsettings
-
-*   The [Command Line Interface][cli] now accepts a `--extensions_config` (or `-c`) 
-    option which accepts a file name and passes the parsed content of a [YAML] or 
-	[JSON]   file to the [`extension_configs`][ec] keyword of the `markdown.Markdown`
-	class. The contents of the YAML or JSON must map to a Python Dictionary which 
-	matches the format required by the `extension_configs` keyword. Note that 
-	[PyYAML] is required to parse YAML files.
-
-[cli]: cli.html#using-extensions
-[YAML]: http://yaml.org/
-[JSON]: http://json.org/
-[PyYAML]: http://pyyaml.org/
-
-*   The [admonition extension][ae] is no longer considered "experimental."
-
-[ae]: extensions/admonition.html
-
-*   There have been various refactors of the testing framework. While those changes
-    will not directly effect end users, the code is being better tested which will 
-    benefit everyone.
-
-*   Various bug fixes have been made.  See the
-    [commit log](https://github.com/Python-Markdown/markdown/commits/master)
-    for a complete history of the changes.