Merge pull request #52 from mpickering/master

Fixes to (5) and (6)
TeX reader: improved parsing inside \text{}.

Accents are now properly handled.
Added a test, src/text.tex.
Removed obsolete .xhtml writer tests.
Removed unneeded import.
Got mathjax preview working in texmath.html demo.
texmath demo formatting tweak.
Added some haddock comments to Types.
Changed EScaled to use a Double instead of a String.
ESpace improvements:

* Use max 3 decimal places in output.
* Fixed OMML writer so approximate width matches are used.
TeX writer: Improved logic for array-like environments.

* Ensures that if we don't have amsmath, we ONLY use array.
TeXMath Reader: Added symbol type lookup to unicode parsing
MathML Writer: Explicitly write accent=False for characters which could be interpreted as accents
TeXMath Reader: Added recognition of escaped space in text environment
MathML Reader: Potential fences which are not actually fences are now constructed with the correct type
Standardised sqrt behavior.

Some readers and writers were expecting arguments in different
positions. It is now standardised across all modules - the correct order
is index followed by base (the same order as in latex). This differs
from the MathML ordering (which is base followed by index).