Resolves Issue #47.
+ Added a DisplayMath/InlineMath selector to Math inlines.
+ Markdown parser yields DisplayMath for $$...$$.
+ LaTeX parser yields DisplayMath when appropriate. Removed
mathBlock parsers, since the same effect is achieved by the math
inline parsers, now that they handle display math.
+ Writers handle DisplayMath as appropriate for the format.
+ Changed -m option to use LaTeXMathML rather than ASCIIMathML.
LaTeXMathML is closer to LaTeX in its display of math, and
supports many non-math LaTeX environments.
+ Modified HTML writer to print raw TeX when LaTeXMathML is
being used instead of suppressing it.
+ Removed ASCIIMathML files from data/ and added LaTeXMathML.
+ Replaced ASCIIMathML with LaTeXMathML in source files.
+ Modified README and pandoc man page source.
+ Modified web page.
+ Added --latexmathml option (kept --asciimathml as a synonym
for backwards compatibility)
+ Modified tests accordingly; added new tests for display math.
git-svn-id: https://pandoc.googlecode.com/svn/trunk@1409 788f1e2b-df1e-0410-8736-df70ead52e1b
