[omxplayer] Merge in latest dvdplayer changes
[dvdplayer] Make players pointers rather than objects
[dvdplayer] Create a base class for audio and video players
[omxplayer] Rework trickplay to reduce changes to dvdplayer
[dvdplayer] Support omxplayer as a variant of dvdplayer
[players] Mark the render features as deprectated and add an OMX prefix
[players] Remove no longer used visualisation callback mechanism
[players] Allow choice of omxplayer through acceleration settings
[players] Remove omxplayer as separately selectable player