[Zpt] HTML support for METAL/TAL

[Guido van Rossum]

>   I've checked in updates to the HTML parser for TAL so that it stands
> a chance of being used with METAL/TAL in Zpt.

Thanks, Fred!

> I think some work is
> still needed for intermediate code generation; not sure exactly what's
> needed yet.

That's easy -- the current code doesn't yet do METAL macro expansion
nor TAL evaluation.  I'm going to rip that code out of TALParser, move
it into TALGenerator, and then invoke it from HTMLTALParser.  Joy will
abound all around.

>   I'll be adding more test cases as well.

Please do.  Please also look into what happens when I call

    driver.py -h test/test2.xml

This raises an AssertionError.  I think that test file is valid XHTML,
so I think it should not bail out.  The same happens for test7.xml.

--Guido van Rossum (home page: http://www.python.org/~guido/)