add support for icedove

Previously there was no support for Icedove, which is the rebranded
Debian version of the Thunderbird e-mail client, and support for this
client has been requested on the GNOME Shell extensions website.

Using the existing code supporting Thunderbird I added code to support
Icedove (mostly just copy, paste, rename) and then tested all Icedove
menu items with GNOME Shell 3.4.2 in Debian GNU/Linux 7.0 (wheezy).
Czech language support
add Afrikaans language support
add Hungarian language support
Merge branch 'hungarian' into translation
fix missing end quote in Czech po file
generate mo files for Czech, Hungarian & Afrikaans
Merge pull request #2 from sinisterstuf/master

Add language support & support for Icedove