Fix fontmake integration

[madig]

This PR depends on

• Handle data and images dirs linebender/norad#176
• Unlazify data and images on comparison fonttools/ufoLib2#165.

[madig]

Groan. The test test_mti_sources fails because fontmake first uses build_master_ufos to create master UFOs plus a Designspace with the MTI data inserted but then continues on to run_from_designspace which reloads the data back from disk (needlessly). Of course iondrive doesn't implement data dir handling yet, so the MTI data is lost...

[madig]

Todo: test if object libs actually make it to Python-land 🤔

[simoncozens]

Can't we just say that if you must use MTI feature code, you don't deserve to have nice things? :-)

[madig]

Agreed, but I still want data and image handling in norad :)

[madig]

Todo: look into the limited python API to make wheels that work cross-py-version

[anthrotype]

Last time I tried, abi3 wheels didn't work on Windows. But +1 as it'd still reduce the number of wheels to build overall for Mac and Linux at least.