Comedilib.pdf can now be generated with

Comedilib.pdf can now be generated with
dblatex -t pdf ./comedilib.xml

There were two major issues in the comedilb.xml:
1) there were too many nested sections so that
   latex ran out of sub-sub-sub-sub-sections.
2) A section needs a title and can no longer
   exist without one. The first line
   of the textfiles contains now the title
   and will be inserted by mkref into the xml file.

todo: switch from xmlto to dblatex for the pdf generation
and re-enable it in the makefile.