
- html.py should be made to produce valid (x)html, this requires

   i) extending the paragraph_nestable concept to observe all html nesting rules - see http://www.cs.tut.fi/~jkorpela/html/nesting.html
   
   ii) html quoting in the _text method.

- better unit tests

- make usage easier

- decrease amount of spaghetti code in stng and document
