Add support for separated widgets for each party member

[foglio1024]

Do something similar to game: floating party members and the rest of the raid in current window layout.
It will be another window mode which will be optional.

• User can move windows around and positions will be saved individually.
• User can set role (maybe even name?) preferences for each widget (this should be class-dependent)

Optionally:

• Make specific group members "detachable" from main window (add a limit?)
• Make individual widgets resizable horizontally