Fix html5lib#72: rewrite the sanitizer to be a treewalker filter only.

As we no longer need the sanitizer to be shared between a filter and
a tokenizer, move the entire sanitizer to the filter module.

Also, replace the existing, tiny sanitizer testsuite with the one
in html5lib-tests.

Author: gsnedders

CHANGES.rst

@@ -7,9 +7,12 @@ Change Log
 Released on XXX
 
 * Added ordereddict as a mandatory dependency on Python 2.6.
+
 * Added ``lxml``, ``genshi``, ``datrie``, ``charade``, and ``all`` extras that
   will do the right thing based on the specific interpreter implementation.
 
+* Sanitizer change XXX
+
 
 0.9999999/1.0b8
 ~~~~~~~~~~~~~~~