W3C Compliant HTML Parser to replace current std/htmlparser

[xTrayambak]

Chawan's HTML parser is really nice, it'd be nice if a few maintainers could be 
allocated to work on it in the stdlib itself, this could even be a really good 
selling point for Nim, but alas, HTML parsers are not all that easy to maintain 
on par with the standards and the quirks of the past.