v0.37

 - Removed Index -> add_conflict() (Incompatible change) (GH#97)
 - Index -> read() now takes an optional force argument (GH#97)
 - Added Raw -> features() method. This may be used to query the features
    built into libgit2 (and thus Git::Raw).
 - Added Repository methods (GH#97):
    + Repository -> cherry_pick()
    + Repository -> revert()
 - Update libgit2 to df19219 (GH#99,GH#102)
 - Added Index methods (GH#100):
    + Index -> capabilities()
    + Index -> path()
    + Index -> add_all()
    + Index -> remove_all()
 - Improved documentation (GH#101)
 - Improved the error model (GH#101)
    All errors are now Git::Raw::Error objects. Extended error information
	provided by libgit2 may be queried (code/category/message) via the
	corresponding accessor. All existing code should continue to work as is
	(via "" and bool overloads).
 - Added Error methods (GH#101):
	+ Error -> code()
	+ Error -> category()
	+ Error -> message()
 - Removed constants from Filter (Incompatible change) (GH#101):
   They are now located in the Error namespace.