Code changes to avoid additional unnecessary re-inits.


git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@36514 b3059339-0415-0410-9bf9-f77b7e298cf2
Chose cheaper alpha blend equation.

We do not care about alpha result, so do not request
complicated calculations for it.


git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@36515 b3059339-0415-0410-9bf9-f77b7e298cf2
Improve handling of internal vs. external dvdread/dvdnav

Document that switching dvdread to external also switches
dvdnav.
If dvdnav-config/dvdread-config paths are given, assume
the user wants to use external versions.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@36516 b3059339-0415-0410-9bf9-f77b7e298cf2