Fixes in `utils.math`.
Avoid side-effect of importing "latex2mathml" on "tex2unichar".
(This led to the merge of `\hslash` and `\hbar` also with
"--math-output=html".)
Use MathML element <mi> (identifier) instead of <mo> (operator)
for "mathord" symbols.
Sort ℏ (`\hslash`) as "mathord", not mathalpha in "tex2unichar".
(Avoids "double italisation" with "math2html".)
Some simplifications in "math2html.py": sort ħ (`\hbar`) as mathalpha
so it gets italicised.
git-svn-id: http://svn.code.sf.net/p/docutils/code/trunk@9513 929543f6-e4f2-0310-98a6-ba3bd3dd1d04