read compressed files, suppress absolute paths before creating outputs

[chicks-net]

This patch handles compressed input PSF and filters out absolute paths before writing the output.

[talamus]

I think I will re-write those file access parts to optionally use Compress::Zlib (and degrade gracefully if it is not available), so scripts will also work in Windows environments.

(Many people seem to do their graphics stuff in Windows.)

[chicks-net]

I'm ok with Windows users running my code in cygwin, but if you want to go the extra mile I applaud.

[chicks-net]

Windows users have WSL now too.