MacOSX builtin spellcheck support

It's working pretty good here. Support all languages you have installed
on your system. I've tested it with mixed french, english, spanish and
it work.

I'd like to have comment/feedback about my implementation ( someone can
test this with chinese, japanese, arabic,... ? )

Francis, now that you have fixed the contextual menu, would it be very
hard to have is include the dictionary suggestion ?

I guess the appleSpell files go in other/spell/cocoa
The patch for spell manager is there to support a new HAVE_APPLESPELL
build option