[cleanup] moves IGUIContainer into a separate include and drops the GUIBaseContainer.h include from GUIViewControl.h.
[rbp/omxplayer] Merge with current dvdplayer

To make spotting differences between omxplayer and dvdplayer easier in the future,
this is a pretty slavish copy, including dvdplayer's whitespace and header file includes.
You now get a pretty clean diff between dvdplayer.cpp/dvdplayer.h and omxplayer.cpp/omxplayer.h