Add 579 new characters

Added 579 characters used in mathematics. The mapping is pretty obvious
and non-controversial for them. They were extracted from [1],
regex-cleaned, put in equivset.in, and then I ran console
generate-equivset (saying this just to make sure I did it right).
[1]: http://www.fileformat.info/info/unicode/block/mathematical_alphanumeric_symbols/list.htm

Change-Id: I0c18f109f160454ada9615f82d42f8e976e30808