trunk: modify sliding-window CMVN algorithm to include current frame in window...

trunk: modify sliding-window CMVN algorithm to include current frame in window (note: this code not used in any recipes yet); modify prior-floor in nnet-cpu code to fix problem..

git-svn-id: https://svn.code.sf.net/p/kaldi/code/trunk@3032 5e6a8d80-dfce-4ca6-a32a-6e07a63d50c8