made filter utility less verbose
made filter utility less verbose

Removed counters saying how many rules were read and how many were kept
after filtering. I always forget to check stderr anyway because
filtering takes a long time. If I want to know how big the resulting
grammar is, I will just wc -l it after the fact, and so can everyone
else.

Also changed the error message for FileNotFoundException to be more
general ("could not open file") because according the Java API that is
what that exception is used for.

joshua-decoder/thrax,joshua-decoder/thrax,tdomhan/thrax,joshua-decoder/thrax,tdomhan/thrax,jweese/thrax,tdomhan/thrax,joshua-decoder/thrax,jweese/thrax,jweese/thrax