font_project: use ufo2ft for outline conversion, overlap removal etc.
font_project: use ufo2ft for outline conversion, overlap removal etc.

also, add support for `cff_round_tolerance` (the argument is called
simply `roundTolerance` in ufo2ft.compileOTF but we want to distinguish
it from the other one here called round_instances).

TODO: we probably need to make the ufo2ft filters/compiler/etc. logging
print more info messages as it's now doing all the work.

googlefonts/fontmake,googlefonts/fontmake,googlei18n/fontmake,googlei18n/fontmake