cosmetics in cs.po

Signed-off-by: pieterg <pieterg@users.sourceforge.net>
Updates for show single frame.

- allow h264 still images to be shown (based on showiframe patch from
  Erik slagter)
- vusolo2 (and probably dus2 too) did not properly show single
  iframes in enigma2 with drivers from before 2013. This was very
  noticable when in radio mode.
fix typo in decoder.cpp

Thanks IMS
Merge remote-tracking branch 'openpli/master' into last

Conflicts:
	lib/dvb/decoder.cpp