Add log file during commit.

[typesupply]

Instead of the notes file, write a log. Format sketch:

Commit Message:
This is blah blah blah.

Added Files:
foo.txt

Removed Files:
bar.txt

Changed Files:
blob.png

Changed Fonts:
something.ufo
- info
- kerning
- layer: blah
-- added glyphs:
--- whatever.alt
-- changed glyphs:
--- whatever.alt

This could then be shown in a history tab of the interface.