Order words asc/desc according to usage frequency

[cjrh]

The "google words" text file in the repo has many words listed in order of usage. If this can be incorporated into thesauromatic it will be possible to order the output by "frequency of use". It'll even be possible to add a filter that will exclude uncommon words, perhaps something like

$ thesauromatic --frequency-threshold 5000 <word>

and this will only include words that appear in the most common 5000 words list.