Adds mathvariants introduced in MML3.
For latex input, names used in the unicode-math (LaTeX-package) is used.
Moved unicode replacement from parsing to mathml output.
OMML might not need to have characters replaced, and not all MathML renderers need it either.
In any case, it certainly isn't necessary to add to parsing stage. For MathML output, this should eventually become optional, or removed completely.
Corrected OMML output for bold italic sans serif as suggested by jgm.
Removed unnecessary symbols, frac12 should be interpreted as frac{1}{2} (as it is in latex).
Having symbols like ½ show up is not preferable in any output except ascii.
Updated tests for latest changes.
Skip labels as if comments.
Added test 22.
Added labels test.
Version bump to 0.6.1.
Version bump to 0.6.1.1, add ToUnicode module to cabal file.
Gobble whitespace after formula as well as before.

This also ensures that labels after formulas are parsed.
Fixed \dot and \ddot.
Updated version to 0.6.1.2.
Added \Upsilon.
Version bump to 0.6.1.3.
OMML:  Don't italicize math operators like sin.
Version bump to 0.6.1.4
Fixed order of arguments in \overset, \underset, \stackrel.

Closes #16.
Version bump to 0.6.1.5.