This is the makeshift doc generator until NDoc works.
Stylistic matters are of very little concern, but the docs should
still be XHTML conformant.

The build system is multi-stage, it effectively works like this:
* Original docs (built by mcs for now): glib-sharp-docs.xml, ...
* netdoc_pp.pl preprocesses these into a cleaner format:
   glib-sharp-docs-stage1.xml, ...
* introspect.exe adds type information from the assembly at hand:
   glib-sharp-docs-stage2.xml, ...
* netdoc.xsl (via xsltproc) translates this xml file into XHTML:
   glib-sharp-docs.html

Plans for the future are listed in TODO.