Don’t calculate whole sets of unicode codepoints
Don’t calculate whole sets of unicode codepoints

_getUnicodeRangeSets used to calculate sets containing lots of numbers, only to
get intersections between a set and ranges. Creating and manipulating a lot of
big sets requires a lot of memory.

The function has been replaced by _getUnicodeRanges, returning a list of range
starts boundaries and a list of range stops + corresponding bits.

Tests on intersectUnicodeRanges save about 130 MB (!) of RAM, with no
significant speed penalty.

fonttools/fonttools,googlefonts/fonttools