Rename picklister-2ps => picklisttops

This is a CUPS filter and should not be called via the wrapper.
Pass command as first argument

The conversion to using the wrapper script broke the watermark script.
It was trying to invoke an executable containing a space rather than
the wrapper.
Filter output through ps2ps

The printer did not like the concatenated output.  Filter it through
ps2ps to clean this up.
Add support for filtering to PDF

If the CUPS filter is invoked with arg[0] ending with "topdf" it will
output PDF instead of Postscript.  Adding an entry into the CUPS filter
directory like this should do the trick:

  $ ln -s picklisttops picklisttopdf