Improve comments.
Shorten the path used for the PS1 prompt, from /w to /W.
VimDiff: Ignore .git files.
Add 'ansi' terminal, for use with Solarized.
- Use $HOME not ~ for my homedirectory to prevent errors with some
  programs like git
- Use Solarized dark background instead of 'chocolate'.
- Add a few more things to DirDiffExcludes
Cosmetic change