trunk,nnet1: adding tool 'feat-to-post', Converts features into posterior format, is used to specify NN training targets when training autoencoder.



git-svn-id: https://svn.code.sf.net/p/kaldi/code/trunk@4676 5e6a8d80-dfce-4ca6-a32a-6e07a63d50c8
trunk,nnet1: adding autoencoder example, demonstrating how to train NN for regression problem



git-svn-id: https://svn.code.sf.net/p/kaldi/code/trunk@4677 5e6a8d80-dfce-4ca6-a32a-6e07a63d50c8
trunk: modifying gpu-based nnet2 training code to do the I/O and input-data formatting in a separate thread from the main training thread (substantial speed improvement).

git-svn-id: https://svn.code.sf.net/p/kaldi/code/trunk@4680 5e6a8d80-dfce-4ca6-a32a-6e07a63d50c8