Take multiple-screens into account when trying to get fullscreen controller
into center of current physical screen.

Basicly same as mplayer/libvo/x11_common.c does.

Close #2196

Signed-off-by: Rémi Denis-Courmont <rdenis@simphalempin.com>

Introduction of an abstractController, that can:
- create most of the interface controller widgets
- execute their actions

All buttons connect themselve to a mapper and a doAction( id_action )
that centralize everything. The Action could go into a mainActionner, I guess. Opinions?

This cleans a lot the signal and exchanges between MI and Controller,
between Controller and FSC. The buttons do their own cooking and connect
directly to THEMIM or to some of the few signals of the Controller
(inputExist, inputHasVideo, inputCanRecord)

This reworks most of the HACKS of Teletext Buttons and AtoB Buttons

The FSC inherit from AbstractController and not Controller, which remove the b_fscreation HACK.

There will be some regressions, I tried my best to minimize them.

The code is generic enough to be able to customize the toolbars now. HAVE FUN!

Each susbcriber has its own ring buffer already.

I don't quite understand why Qt4 would subscribe to messages all the
time rather than only when the dialog is on.

It should close #2195.