Support for ts3server query commands

[Chrisg2000]

Adds support for all now and in future available ts3server query commands.
In Events.py: data field should be a dict with accessible entries rather than a list of keys of an inaccessible dict

[Murgeye]

Love it! Thanks for your contribution.

That list(data) stuff was written a long time ago, I cannot even remember what the idea was behind that. Maybe a copy of the data dictionary would be better in case the data is ever used anywhere else? (Should not happen for now, but who knows)

Anyways, approved!

[Chrisg2000]

Thanks for accepting my changes.
Although I forgot to add something which I will add in my next pull request.

I think it is not needed to use a copy of the data dictionary. The _data dict is available through the data property, which is read-only, and all necessary properties for a event are retrieved via the original data variable inside the init function head.