Add complex checkout test and then fix checkout

This started as a complex new test for checkout going through the
"typechanges" test repository, but that revealed numerous issues
with checkout, including:

* complete failure with submodules
* failure to create blobs with exec bits
* problems when replacing a tree with a blob because the tree
  "example/" sorts after the blob "example" so the delete was
  being processed after the single file blob was created

This fixes most of those problems and includes a number of other
minor changes that made it easier to do that, including improving
the TYPECHANGE support in diff/status, etc.

3 files changed, 25 insertions, 5 deletions

diff --git a/include/git2/checkout.h b/include/git2/checkout.h
index ef3badbe9..fb1a23030 100644
--- a/include/git2/checkout.h
+++ b/include/git2/checkout.h
@@ -21,12 +21,27 @@
  */
 GIT_BEGIN_DECL
 
-enum {
+/**
+ * Checkout behavior flags
+ *
+ * These flags control what checkout does with files.  Pass in a
+ * combination of these values OR'ed together.
+ *
+ * - GIT_CHECKOUT_DEFAULT: With this value, checkout does not update
+ *   any files in the working directory.
+ * - GIT_CHECKOUT_OVERWRITE_MODIFIED: When a file exists and is modified,
+ *   replace the modifications with the new version.
+ * - GIT_CHECKOUT_CREATE_MISSING: When a file does not exist in the
+ *   working directory, create it.
+ * - GIT_CHECKOUT_REMOVE_UNTRACKED: If an untracked file in encountered
+ *   in the working directory, delete it.
+ */
+typedef enum {
 	GIT_CHECKOUT_DEFAULT			= (1 << 0),
 	GIT_CHECKOUT_OVERWRITE_MODIFIED	= (1 << 1),
 	GIT_CHECKOUT_CREATE_MISSING		= (1 << 2),
 	GIT_CHECKOUT_REMOVE_UNTRACKED	= (1 << 3),
-};
+} git_checkout_strategy_t;
 
 /* Use zeros to indicate default settings */
 typedef struct git_checkout_opts {
diff --git a/include/git2/diff.h b/include/git2/diff.h
index 551e525ef..1d32d9ad2 100644
--- a/include/git2/diff.h
+++ b/include/git2/diff.h
@@ -56,6 +56,9 @@ GIT_BEGIN_DECL
  * - GIT_DIFF_DONT_SPLIT_TYPECHANGE: normally, a type change between files
  *   will be converted into a DELETED record for the old file and an ADDED
  *   record for the new one; this option enabled TYPECHANGE records.
+ * - GIT_DIFF_SKIP_BINARY_CHECK: the binary flag in the delta record will
+ *   not be updated.  This is useful if iterating over a diff without hunk
+ *   and line callbacks and you want to avoid loading files completely.
  */
 enum {
 	GIT_DIFF_NORMAL = 0,
@@ -73,7 +76,9 @@ enum {
 	GIT_DIFF_DISABLE_PATHSPEC_MATCH = (1 << 11),
 	GIT_DIFF_DELTAS_ARE_ICASE = (1 << 12),
 	GIT_DIFF_INCLUDE_UNTRACKED_CONTENT = (1 << 13),
-	GIT_DIFF_DONT_SPLIT_TYPECHANGE = (1 << 14),
+	GIT_DIFF_SKIP_BINARY_CHECK = (1 << 14),
+	GIT_DIFF_INCLUDE_TYPECHANGE = (1 << 15),
+	GIT_DIFF_INCLUDE_TYPECHANGE_TREES = (1 << 16),
 };
 
 /**
diff --git a/include/git2/tree.h b/include/git2/tree.h
index e5261417c..2ee1f4afa 100644
--- a/include/git2/tree.h
+++ b/include/git2/tree.h
@@ -100,7 +100,7 @@ GIT_EXTERN(git_tree_entry *) git_tree_entry_dup(const git_tree_entry *entry);
  * @param tree a previously loaded tree.
  * @return object identity for the tree.
  */
-GIT_EXTERN(const git_oid *) git_tree_id(git_tree *tree);
+GIT_EXTERN(const git_oid *) git_tree_id(const git_tree *tree);
 
 /**
  * Get the number of entries listed in a tree
@@ -108,7 +108,7 @@ GIT_EXTERN(const git_oid *) git_tree_id(git_tree *tree);
  * @param tree a previously loaded tree.
  * @return the number of entries in the tree
  */
-GIT_EXTERN(unsigned int) git_tree_entrycount(git_tree *tree);
+GIT_EXTERN(unsigned int) git_tree_entrycount(const git_tree *tree);
 
 /**
  * Lookup a tree entry by its filename