Merge pull request #49 from mpickering/master

MathML Writer: Added position information to fences
Updated tests form 'form' attribute addition in mathml output.
Removed texmath.xhtml.  texmath.html is fine.
Removed old cgi/sample.html.
Reformatted cabal description for narrower col width.
Minor haddock changes.
Updated texmath.html demo.
Style tweaks on demo.
More demo tweaks.
Added option to do round-trip tests in test suite.

test-texmath --round-trip

This will do round-trip tests INSTEAD OF the ordinary tests.
MathML reader:  use styled identifier, not EText, for mi w/ mathvariant.

This seems more semantically correct, and agrees with how the TeXMath
reader works.
Moved getOperator from TeXMath writer to Shared.
TeXMath writer: Improved writing of identifiers.

We no longer put a \mathoperator{} around everything with
more than one token.

Also, don't print "invisible operators" from MathML.
Updated tests.
MathML reader:  turn some mi's into EMathOperator.

We see if they match Shared.getOperator.
This is necessary since mathml uses <mi>sin</mi> for sin, etc.

Also renamed getOperator in MMLDict to getMathMLOperator to
avoid a conflict with the function from Shared.
Added fromUnicode to Unicode.ToUnicode.
MathML Reader: Stripped outer EGrouped from output
Regen tests