+ Rename some txt2tags file from .txt to .t2t and remove abandoned .txt files.
+ Add program update_html that finds all .t2t documents and updates the
corresponding .html file. It can be invoked with 'make html'.
+ Add style to some .html documents
- Added link to the Prasebook demo. The older demos are no longer labelled NEW.
- Point to www.grammaticalframework.org instead of tournesol.cs.chalmers.se
- Update links to www.cs.chalmers.se to new pages on www.cse.chalmers.se, since
there is no working autmatic redirection.
- got rid of some HTML clutter.
- index.txt was out of sync with index.html. It is now even more out of sync.