fix handling of scale parameter & python 3 compatibility for cli

Add a command line interface

Update font API & merge upper and lower case words when stemming

Has the advantage of producing fewer checks, as most words will be multiples.

downgrade numpy req 

Frequency scaling

fix sorting and normalization: wasn't applied if frequencies were given directly

hopefully fixing cython built

Add pipy install, remove sudo

[MRG] don't use sudo in travis, don't --use-mirror in pip

Include a droid sans mono ttf file

dont --use-mirror

factor out computational part