[Suggestion] Manual syntax highlight

["piranna gmail com" <piranna gmail com>]

Meld show code highlighted using the file extension as reference, but
if extension doesn't correspond to any language or is not detected
(for example, TortoiseSVN meld files end with .mine, .working,
.rev7214, etc) it shows as plain text. It would be a good idea to be
able to set the sintax highlight from a menu option or right click for
every file or for all at a time. Another good idea is that if it's
detected the language at only one file asume it for the other ones.

-- 
"Si quieres viajar alrededor del mundo y ser invitado a hablar en un
monton de sitios diferentes, simplemente escribe un sistema operativo
Unix."
– Linus Tordvals, creador del sistema operativo Linux