Define custom token types

Actually i was thinking of something more like adding a -new type- entry to the type selection element in the edit token form, and two text fields (type name, type label).
This implies that a type with no tokens should be automatically deleted, and i'm not sure this is a good idea.

Your proposition sounds simpler, but i don't like the idea of adding another tab just for a few token types (if any).

Still thinking about it though, can't make up my mind. What do you think ?

Note, you also need a description for token types as well.

Finally i did add another tab with the custom token type list.
I'd like to add edit permissions by token type before commiting this to the dev branch.

Commited (kinda by accident) to branch 7.x-2.x. (it should be visible in a few hours)
Still needs review though.