Symbolic links that abuse case insensitivity to write into .git.

Don't bother trying to recreate the previously created directory
during checkout, for a modest reduction in the number of stats.

The documentation for `git_path_join_unrooted` states that the base
length will be returned, so that consumers like checkout know where
to start creating directories instead of always creating directories
at the directory root.

Checkout can now provide performance data about the number of (some)
syscalls performed using an optional callback.

This structure remains internal-only in maintenance branches.

clone example: don't divide by zero

Local transports don't have data about the size, avoid dividing by
zero in the callback.

This should provide a easier way to see what kinds of changes we have,
and a single place to look at the breaking changes.

  Fix crash in free() when git_buf_grow() fails.

Remove symlinks from the repository

remote: plug leak

Remove the hook symlink from the test resources, so that we can
have a source tree that is easy to zip up and copy around on systems
that don't support symlinks.  Create it dynamically at test execution
instead.

Load prune configuration when a remote is created.

CHANGELOG: we've added git_describe

submodule: declare vars at top of func block

Add appveyor yaml

CHANGELOG: add missing 0.22 changes

Better document `git_merge_commits`

The release after 0.21 is 0.22. Add a new heading for the changes since
0.22.

Bump the version number to 0.22.0 and the SOVERSION to 22.

`git_merge_commits` (and thus `git_merge`) do not use the same
strategy as `git-merge-recursive` wherein they can produce an
artificial common ancestor that is the merge of all common
ancestors.  Document this accordingly.

Fixed internal push state not being cleared when calling git_remote_download()

Include git2/common.h in sys/openssl.h.

git_remote_download() must also clear the internal push state resulting from a possible earlier push operation. Otherwise calling git_remote_update_tips() will execute the push version instead of the fetch version and among other things, tags won't be updated.

Fixed git_revert() documentation