[Evolution] Spell check languages

[Mertens Bram <bram-mertens linux be>]

Hi,

I have found that Evolution uses the gnome-spell package, but I can't
seem to find the homepage for this package or the project it belongs
to...

(There's no man page for gnome-spell)

I'm looking for info about the following:
How to find out which languages are installed on my system (I have
gnome-spell-0.4.1-0.7x installed)
A list of codes for these languages (I'm especially looking for dutch, I
suppose it's nl but I'd like to be sure)
where to find and how to install new languages if necessary...

Thanks in advance for any hint!

Bram