Add support for these ranges

[LettError]

Issue from @FrankFolf on GlyphBrowser repo:
LettError/glyphBrowser#27

U+2900-U+297F	Supplemental Arrows-B
U+2980-U+29FF	Miscellaneous Mathematical Symbols-B
U+2A00-U+2AFF	Supplemental Mathematical Operators
U+2B00-U+2BFF	Miscellaneous Symbols and Arrows

[LettError]

@frankrolf do you already have a preference for these names?