OPT: Moved MIME getter as get_mime_type() to general.php. Optimized it to use
the $mime_type_by_extension array first, and only fall back to exiftool if
that did not know the extension, instead of always overwriting the result of
the relatively expensive exiftool call.


git-svn-id: http://svn.montala.net/svn/resourcespace@4629 c08608d7-6e46-0410-86ca-f2a6f1370df5