Pygit2

- Update to libgit2 v0.26
[713](https://github.com/libgit2/pygit2/pull/713)
- Drop support for Python 3.2, add support for cffi 1.10
[706](https://github.com/libgit2/pygit2/pull/706)
[694](https://github.com/libgit2/pygit2/issues/694)
- New `Repository.revert_commit(...)`
[711](https://github.com/libgit2/pygit2/pull/711)
[710](https://github.com/libgit2/pygit2/issues/710)
- New `Branch.is_checked_out()`
[696](https://github.com/libgit2/pygit2/pull/696)
- Various fixes [706](https://github.com/libgit2/pygit2/pull/706)
[707](https://github.com/libgit2/pygit2/pull/707)
[708](https://github.com/libgit2/pygit2/pull/708)

- Add support for Python 3.6
- New support for stash: repository methods `stash`, `stash_apply`,
`stash_drop` and `stash_pop`
[695](https://github.com/libgit2/pygit2/pull/695)
- Improved support for submodules: new repository methods
`init_submodules` and `update_submodules`
[692](https://github.com/libgit2/pygit2/pull/692)
- New friendlier API for branches & references: `Repository.branches`
and `Repository.references`
[700](https://github.com/libgit2/pygit2/pull/700)
[701](https://github.com/libgit2/pygit2/pull/701)
- New support for custom backends
[690](https://github.com/libgit2/pygit2/pull/690)
- Fix `init_repository` crash on None input
[688](https://github.com/libgit2/pygit2/issues/688)
[697](https://github.com/libgit2/pygit2/pull/697)
- Fix checkout with an orphan master branch
[669](https://github.com/libgit2/pygit2/issues/669)
[685](https://github.com/libgit2/pygit2/pull/685)
- Better error messages for opening repositories
[645](https://github.com/libgit2/pygit2/issues/645)
[698](https://github.com/libgit2/pygit2/pull/698)

- Upgrade to libgit2 0.25
[670](https://github.com/libgit2/pygit2/pull/670)
- Now Commit.tree raises an error if tree is not found
[682](https://github.com/libgit2/pygit2/pull/682)
- New settings.mwindow_mapped_limit, cached_memory, enable_caching,
cache_max_size and cache_object_limit
[677](https://github.com/libgit2/pygit2/pull/677)

- Unit tests pass on Windows, integration with AppVeyor
[641](https://github.com/libgit2/pygit2/pull/641)
[655](https://github.com/libgit2/pygit2/issues/655)
[657](https://github.com/libgit2/pygit2/pull/657)
[659](https://github.com/libgit2/pygit2/pull/659)
[660](https://github.com/libgit2/pygit2/pull/660)
[661](https://github.com/libgit2/pygit2/pull/661)
[667](https://github.com/libgit2/pygit2/pull/667)
- Fix when libgit2 error messages have non-ascii chars
[651](https://github.com/libgit2/pygit2/pull/651)
- Documentation improvements
[643](https://github.com/libgit2/pygit2/pull/643)
[653](https://github.com/libgit2/pygit2/pull/653)
[663](https://github.com/libgit2/pygit2/pull/663)

- New `Repository.listall_reference_objects()`
[634](https://github.com/libgit2/pygit2/pull/634)
- Fix `Repository.write_archive(...)`
[619](https://github.com/libgit2/pygit2/pull/619)
[621](https://github.com/libgit2/pygit2/pull/621)
- Reproducible builds
[636](https://github.com/libgit2/pygit2/pull/636)
- Documentation fixes
[606](https://github.com/libgit2/pygit2/pull/606)
[607](https://github.com/libgit2/pygit2/pull/607)
[609](https://github.com/libgit2/pygit2/pull/609)
[623](https://github.com/libgit2/pygit2/pull/623)
- Test updates [629](https://github.com/libgit2/pygit2/pull/629)

- Update to libgit2 v0.24
[594](https://github.com/libgit2/pygit2/pull/594)
- Support Python 3.5
- New dependency, [six](https://pypi.org/project/six/)
- New `Repository.path_is_ignored(path)`
[589](https://github.com/libgit2/pygit2/pull/589)
- Fix error in `Repository(path)` when path is a bytes string
[588](https://github.com/libgit2/pygit2/issues/588)
[593](https://github.com/libgit2/pygit2/pull/593)
- Fix memory issue in `Repository.describe(...)`
[592](https://github.com/libgit2/pygit2/issues/592)
[597](https://github.com/libgit2/pygit2/issues/597)
[599](https://github.com/libgit2/pygit2/pull/599)
- Allow testing with [tox](https://pypi.org/project/tox/)
[600](https://github.com/libgit2/pygit2/pull/600)