Dropsdl

This pull request rids us of SDL for events and window system.

I'm a bit hesitant to the fix for separate screen's. It get a bit messy with extending resolution structure for this. Wasn't sure what the call the value also it's still broken since it need a skin refresh since we apparently have not implemented OnDeviceReset() callbacks on GLX systems.

This tries to replace https://github.com/xbmc/xbmc/pull/848, but it isn't fully complete. So @FernetMenta may have to re-add anything that i've missed.

It clearly need testing.