Change most Comment lines to be GenericName. GenericName should be
used when only one IRC client in installed.

	modified:   share/misc/hexchat.desktop
Change "no" to "nb" for Norsk Bokmål. In norway there is not only
one official language but two.

	modified:   share/misc/hexchat.desktop
Translate Comment in french, german, italian and norwegian bokmål

	modified:   share/misc/hexchat.desktop
Add GTK and IRCClient to Categories. This is Based on:

http://standards.freedesktop.org/menu-spec/latest

	modified:   share/misc/hexchat.desktop