Medusa search improvements

Having flu inspired me to work feverishly on Medusa. I've completely restructured msearch-gui. It's much more stable, and I squashed some bugs in the process. I cut some features I felt were frivolous. I don't think apps should be making private solutions for public problems: gnome-vfs needs a gnome_vfs_uri_is_valid, GDate should handle time. I'll need to spend some time on other libs and Storage soon to advance Medusa.

A word to the wise. Just because Medusa supports 'emblems do not include ...' doesn't mean you should use it. I accidentally searched for anything that wasn't and application. The result set of more 200,000 files was returned in seconds, but displaying that many files in a window crippled my machine to 30 minutes before I could kill it. I think I'll add a sanity to msearch-gui to clamp the results to no more than a few hundred files.