c9259c4723
Fixes https://github.com/fonttools/fonttools/issues/1112
This implements the same logic found in harbfuzz hb-ot-tag.cc to
convert between Unicode (or ISO 15924) script codes to OpenType script
tags as defined at:
https://www.microsoft.com/typography/otspec/scripttags.htm
461a605fde/src/hb-ot-tag.cc (L127)