Add support for recording PRs.

Also some minor fixes:

 - Set some hardcoded values as #defines.

 - out->user should be exclam + 1 and not exclam + 2. The presence of
   the tilde simply means the host does not have an accessible identd
   and should still be considered as part of user name.
Add a list of allowed lifts.

More small changes:

 - Normalize all lifts to lowercase.

 - Enable -Wall -Werror.
More const qualifiers.
Add some preliminary support for retrieving PRs.
Fix some really shitty commenting.
Get rid of some excessive strlen() calls.
Merge pull request #1 from rfw/master

Actually implement PR functionality in PRBot.