Joost STX processor

It would be useful to add an "ignore DTD option" to the command-line
parameters.

Sometimes people don't need the DTD file for a transformation and would
like to ignore it.

For example, if doctype reffers to an online DTD file, you must be
connected to internet to be able to process the xml, although you don't
need the DTD.

Microsoft MSXSL does have that option (-xe).

Thanks for your work!