Cast to `uint32_t` instead of `uint32`
Add index parameter to `enumerateHunksUsingBlock`
Move blame creation method to GTRepository+Blame.h

Also move  `GTBlameOptions*` flags to the new category.
Also includes a bunch of fixes for review notes.
Remove `git_oid_struct`
Update `isBoundary` documentation to be clearer.
Subclass `isEqual:` directly.
`GTBlameHunk.class` instead of `self.class`