Fixes #127 (that was quite an outstanding issue).

Rationale:

The tree objects on Git are stored and read following a very specific
sorting algorithm that places folders before files. That original sort
was the sort we were storing on memory, but this sort was being queried
with a binary search that used a simple `strcmp` for comparison, so
there were many instances where the search was failing.

Obviously, the most straightforward way to fix this is changing the
binary search CB to use the same comparison method as the sorting CB.
The problem with this is that the binary search callback compares a path
and an entry, so there is no way to know if the given path is a folder
or a standard file.

How do we work around this? Instead of splitting the `entry_byname`
method in two (one for searching directories and one for searching
normal files), we just assume that the path we are searching for is of
the same kind as the path it's being compared at the moment.

	return git_futils_cmp_path(
		ksearch->filename, ksearch->filename_len, entry->attr & 040000,
        entry->filename, entry->filename_len, entry->attr & 040000);

Since there cannot be a folder and a regular file with the same name on
the same tree, the most basic equality check will always fail
for all comparsions, until our path is compared with the actual entry we
are looking for; in this case, the matching will succeed with the file
type of the entry -- whatever it was initially.

I hope that makes sense.

PS: While I was at it, I switched the cmp methods to use cached values
for the length of each filename. That makes searches and sorts
retardedly fast -- I was wondering the reason of the performance hiccups
on massive trees; it's because of 2*strlen for each comparsion call.

mode field of git_index_entry_unmerged is array of unsigned ints. It's
unsafe to cast pointer to an element of the array to long int *. It may
cause overflow in git_strtol32().

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

Type casting usually points to some trick or bug. It's better not hide
it between useless type castings.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

index_initialize() calls assert() for arguments on its own. No need to
call it twice.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

Remove dummy wrapper around git_vector_sort().

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

git_vector_bsearch2() calls git_vector_sort(). No need to call it
directly.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

git_index_clear() frees index->entries and index->unmerged. No need to
free it once again.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

Add parrot-libgit2 to the list of language bindings in the readme

Fix more memory leaks

reference_rename: make sure old_name gets freed

Signed-off-by: Carlos Martín Nieto <cmn@elego.de>

Signed-off-by: Carlos Martín Nieto <cmn@elego.de>

Signed-off-by: schu <schu-github@schulog.org>

Finish to hide git_pkt from external API.

reflog: Fix reflog writer/reader

Some of the WIP API calls have been hidden in preparation for the next
minor release.

 - Use a space to separate oids and signature
 - Enforce test coverage
 - Make test run in a temporary folder in order not to alter the test repository

Fix MSVC compilation warning

The `hashfile` function has been moved to ODB, next to `git_odb_hash`.

Global state has been removed from the dirent call in `status.c`,
because global state is killing the rainforest and causing global
warming.

Throws GIT_ENOTFOUND error if given a filename that is not in
HEAD, index, nor the work tree.

Refactored copy of test repo to a function.

Add git_status_file to be able to retrieve status of single file by
supplying a path.

Add git_status_foreach() to run a callback on each file passing the path
and a status value.

Add git_status_hashfile() to get blob's object id for a file without adding
it to the object database or needing a repository at all.
This functionality is similar to `git hash-object` without '-w'.