Support Unicode 11 Mathematical Standardized Variants

[davidmjones]

See https://www.unicode.org/Public/11.0.0/ucd/StandardizedVariants.txt

[tiroj]

We have glyphs for some (most?) of these already, but they are not mapped to Variant Selector 1 (U+FE00) sequences. This is relatively easy to do, but means adding a format 14 cmap table to the fonts. This will make the sources a bit less friendly to editing if someone wants to fork the fonts, since a lot of font tools won't write format 14 cmap.

[Update: have confirmed that we have glyphs for all these variants, excepting 0030 FE00; short diagonal stroke form; # DIGIT ZERO which we'll add to the Math font, and FF10 FE00; short diagonal stroke form; # FULLWIDTH DIGIT ZERO which is specific to East Asian typography, not supported in the STIX fonts.]

[tiroj]

Logged to add support in 2.0.1

[davidmjones]

These look good except for two things:

• The mapping for 0030 FE00 to zero.VS1 is missing from the format 14 cmap table.
• The default and variant versions of U+229C are swapped.