Point to the libgit2 blame branch.
Blame, yo!
Add support for `min_line` and `max_line` blame options.
Expose blame hunk data.
Add newest_commit and oldest_commit options.
Rename Blame#hunk_by_line to Blame#for_line.
Add some more documentation.
Handle invalid index positions and line numbers correctly.
Add Blame#each and include the Enumerable module into Blame.
Improve docs a tiny bit.