Tvheadend

This is my best, feel free to use this patch. I think it is not the best way, but a base to work on.
Sincerely i don't think that I will present a pull request for this for these reasons:

- often channels have multiple languages then, in clients with poor grouping abilities (kodi?) there are lot of language groups with the same channels (from a big list as yours you can get dozens of groups only a little smaller) and i feel this a confusing way to group them.

- lots of channels (eg. encrypted in my setup) don't have the lang attribute set, so you can miss them in groups.

- coding may be really wrong as i'm not a programmer.

May be this a discussion base for skilled programmers like Jaroslav or Adam?