Rough In New Sanitizer

Start work (which may not pan out) on a new sanitizer. Right now, it passes
all but 1 of the HTML5lib Sanitizer's unit tests. But it doesn't do much
of anything to ensure well-formedness. This is not an issue for Maruku-processed
content, but it is a concern for <nowiki> blocks.

(One solution would be to use the HTML5lib parser on <nowiki> blocks.)

In any case, this baby is 3 times as fast as the HTML5lib sanitizer.

vendor/plugins/maruku/lib/maruku/ext/math/mathml_engines/itex2mml.rb

@@ -4,7 +4,7 @@ module MaRuKu; module Out; module HTML
 	def convert_to_mathml_itex2mml(kind, tex)
 		begin
 			if not $itex2mml_parser
-				require 'sanitize'
+				require 'stringsupport'
 				require 'itextomml'
 				$itex2mml_parser =  Itex2MML::Parser.new
 			end