replace jtidy with validator.nu htmlparser

jtidy only really accepts late 20th century html and has several
unfixed isues (like not being thread safe) that make its use in a
server process undesirable.

The validator.nu parser implements the latest HTML5 specification and
so allows a far greater flexibility in visualization stylesheets.

The only problem is that several existing games rely on the fact that
jtidy moves ill-places style elements into the document head where
they belong, so that behaviour had to be reimplemented.
add htmlparser license document
add svg rendering to visualizations
remove hard coded dimensions
Merge pull request #42 from fhars/visualization-updates

Visualization updates