Shouldn't have any issues with excpetions anymore at least.
Need to read the PDF reference manual properly to see if
this is the right thing to do...
Fixes #2
Rough initial version of script. Only tested with
a few PDF files. There's a lot of things that could
be improved:
* Add options to list layer names
* Add options for trying to loacate and modify JavaScript
that might affect layer visibility (in Adobe Reader).
* Error handling...
* Cleanup... better ways of using pikedpdf..?