EACS was just DVI (high nibble first) with stereo and mono modes, while
old DVI was mono only.
This unifies both decoders, so DVI_IMA (not interleaved) works with mono
and stereo while DVI_IMA_int (interleaved) forces mono.
Some metas needed to explicitly set DVI_IMA_int but others work with no
change.
changed _noninterleaved functions to _int and changed related descriptions appropriately
added an _int version of SDX2 and reverted to pre-322 behavior for normal deocder
made the various get_high_nibble globals all be the same vgmstream->get_high_nibble for thread safety and code consolidation (this required some changes to make decode functions take VGMSTREAM rather than VGMSTREAMCHANNEL)
git-svn-id: https://vgmstream.svn.sourceforge.net/svnroot/vgmstream@323 51a99a44-fe44-0410-b1ba-c3e57ba2b86b
