Added Text.Pandoc.Readers.TeXMath and changed default handling of math.

+ Text.Pandoc.Readers.TeXMath exports readTeXMath, which reads raw TeX
  math and outputs a string of pandoc inlines that tries to render it
  as far as possible, lapsing into literal TeX when needed.
+ Added Text.Pandoc.Readers.TeXMath to pandoc.cabal + ghc66 version.
+ Modified writers so that readTeXMath is used for default HTMl output
  in HTML, S5, RTF, Docbook.
+ Updated README with information about how math is rendered in all formats.
+ Updated test suite.


git-svn-id: https://pandoc.googlecode.com/svn/trunk@1129 788f1e2b-df1e-0410-8736-df70ead52e1b

tests/s5.basic.html

@@ -780,7 +780,33 @@ window.onresize = function(){setTimeout('fontScale()', 50);}</script>
     >Math</h1
     ><ul
     ><li
-      >\frac{d}{dx}f(x)=\lim_{h\to 0}\frac{f(x+h)-f(x)}{h}</li
+      >\frac{<em
+	>d</em
+	>}{<em
+	>dx</em
+	>}<em
+	>f</em
+	>(<em
+	>x</em
+	>)=\lim<sub
+	><em
+	  >h</em
+	  >&#8201;&#8594;&#8201;<em
+	  >0</em
+	  ></sub
+	>\frac{<em
+	>f</em
+	>(<em
+	>x</em
+	>+<em
+	>h</em
+	>)-<em
+	>f</em
+	>(<em
+	>x</em
+	>)}{<em
+	>h</em
+	>}</li
       ></ul
     ></div>
 </div>