fix IE's rules limit - log as warning

Fix DeprecationWarning on inspect.getargspec in python3

Fix DeprecationWarning: PY_SSIZE_T_CLEAN will be required for '#' formats

We see the following warning when scss is used with python 3.8.

  scss/compiler.py:359: DeprecationWarning: PY_SSIZE_T_CLEAN will be required for '#' formats
    for c_lineno, c_property, c_codestr in locate_blocks(rule.unparsed_contents):

This warning was introduced by https://bugs.python.org/issue36381
to warn about an upcoming Python C API change.
The meaning of PY_SSIZE_T_CLEAN is described in
https://python.readthedocs.io/en/stable/c-api/arg.html#strings-and-buffers.

What we need to do are:
* find all usages of PyArg_Parse with # formats and related functions.
  Ensure that the type of the length argument is a Py_ssize_t.
* Add #define PY_SSIZE_T_CLEAN above the #include <Python.h>.

Signed-off-by: Akihiro Motoki <amotoki@gmail.com>

inspect.getargspec() is deprecated in python3 and the usage of
inspect.signature() or inspect.getfullargspec() is recommended.
The only different between getargspec and getfullargspec is
that "keywords" attribute in getargspec() return value corresponds
to "varkw" attribute in case of getfullargspec().
This commit changes the code to try getfullargspec() first and
then fallback to getargspec().

As far as I know [1] IE 11 supports 65534 rules.  BTW fix logging class from
error to warning [2].

[1] https://forums.asp.net/t/2059387.aspx?IE+10+and+11+CSS+Style+Sheet+Rules
[2] bdb02e8d Warning about IE 4095 maximum and improved debug_info

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

Add selector-append function support