[PATCH] Refactor mime.cc

Hi all,
 the attached patch aims to c++-ify and standardize a bit more mime.cc
and the auxiliary classes it contains.

No functional changes.
It'd be nice to change the mime table from being a table of regexes to
a suffix search - after all, all mime extensions recorded there are
suffixes except for the catch-all case.

This code is however not on a critical path, so I'd leave that step
post-stringng.

--
    /kinkie