Nothing functional in there yet.
So far, we're parsing IndicSyllabicCategory.txt and IndicMatraCategory.txt
fils from Unicode Character Database and store them in an array to be used
by the shaper. Also hooked up the shaper, but it does not do anything
right now.
Add support for classic Mongolian script to the Arabic shaper.
Still work to be done around U+180E MONGOLIAN VOWEL SEPARATOR as it
should not be included in the final glyph stream the same way that
ZWNJ, etc should not appear in the final glyph stream.
But the joining part should be done.
There remains the question of how should the U+18A9 MONGOLIAN LETTER ALI
GALI DAGALGA be handled as it has General Category NSM but a letter
nonetheless. For now, our generic logic makes this a joining T instead
of joining D as other Mongolian letters are.