Adding support for HTML5 parser.
Added use \HTML5.
Issue #114: Adding support for withHTML5() and html5qp().
Commiting html5qp() function.

Also modified htmlqp() to use the HTML5 parser if use_parser is
set to 'html5'.
Issue #114: Updated documentation about use_parser.
Updated withHTML().
Added html5, innerHTML5, writeHTML5 and tests.
Merge branch 'master' into feature/html5
Merged feature/html5 branch