changed feature selector so that it removes features both at encode and decode time
removed all mentions of thesaurus in the tokenizer, this functionality belongs in the feature extraction module
fixed another unit test; optimised feature selector so it does not compute feature scores if there is no need for it
un-deleted call to stats_recorder.print_coverage_info, which got left out during refactoring
removed more references to obsolete parameter keep_only_IT
fixed failing consolidator unit test (because of renamed parameters in conf files); removed excessive print statements here and there
changed things a little bit so that feature selection doesn't always have to be enabled all the time
moved data dump after feature selection stage; in the process found a bug where the feature selector was keeping the wrong vocabulary (did not take into account that items have been removed)

I think it is now fixed, but tests are needed: 1) where only k= small number is specified 2) where only ensure_vectors_exist is specified 3) where both are set 4) where neither is set