Changes to lower level scripts for proxy keywords: 1. decomposed generate_proxy_keywords.sh into a language dependent part and language independent part; 2. improved the ATWV performance

git-svn-id: https://svn.code.sf.net/p/kaldi/code/trunk@3504 5e6a8d80-dfce-4ca6-a32a-6e07a63d50c8