Add Repository#RevParse.
Move RevSpec#From and RevSpec#To to struct methods.
Add simple test for `rev-parse HEAD`.
Make a new pointer to pass to git_revparse.
Add Repository#RevParseSingle.
Add Repository#RevParseExt.
Make sure install/lib dir exists. Fixes #104
status data types
add ByIndex, reorder to match other files
add StatusList.EntryCount()
add StatusList() to Repository
start on status tests; fix bug in Repository.StatusList()
add status option support
add StatusFile function
comment out issue with entry count
add git_status_foreach binding
Extract data into a go struct.
Merge pull request #105 from mattes/patch-1

Make sure install/lib dir exists. Fixes #104
Handle empty slices in CreateBlobFromBuffer()

Go won't let us access the zeroth alement of an empty slice, so we need
to figure out if the length is zero and take special action.

This fixes #106.
Update vendored libgit2 version to v0.21.1