diff-mode

Provides support for font-lock, outline, navigation
commands, editing and various conversions as well as jumping
to the corresponding source file.

Inspired by Pavel Machek's patch-mode.el (<pavel@@atrey.karlin.mff.cuni.cz>)
Some efforts were spent to have it somewhat compatible with
`compilation-minor-mode'.

Bugs:

- Reverse doesn't work with normal diffs.

Todo:

- Improve `diff-add-change-log-entries-other-window',
  it is very simplistic now.

- Add a `delete-after-apply' so C-c C-a automatically deletes hunks.
  Also allow C-c C-a to delete already-applied hunks.

- Try `diff <file> <hunk>' to try and fuzzily discover the source location
  of a hunk.  Show then the changes between <file> and <hunk> and make it
  possible to apply them to <file>, <hunk-src>, or <hunk-dst>.
  Or maybe just make it into a ".rej to diff3-markers converter".
  Maybe just use `wiggle' (by Neil Brown) to do it for us.

- in diff-apply-hunk, strip context in replace-match to better
  preserve markers and spacing.
- Handle `diff -b' output in context->unified.