more omxplayer options

although been the best videoplayer on the raspberry the documentation is quite spread out over the net. so here the most useful commands to start a omxplayer:

--loop run a video in a loop
--win 'x1 y1 x2 y2' run video in a window defined by upper left corner(x1,y1) and right bottom corner(x2,y2)
--no-osd display without showing information
--blank showing video and blacking the rest of the screen