Add navi2ch face.

https://github.com/naota/navi2ch
Merge pull request #132 from myuhe/navi2ch

Add navi2ch face.
Fix diff-refine-* colors for highlighting Magit hunks.
Merge pull request #131 from vonavi/master

Fix diff-refine-* colors for highlighting Magit hunks.
Merge remote-tracking branch 'upstream/master'