WIP: Add perl modules needed to build "slic3r" (TODO: clean up Wx expression)

Slic3r is a tool to convert a digital 3D model into printing
instructions for your 3D printer. I'll add it in the next commit.

A couple of old modules were no longer available on CPAN so I bumped
them.

XMLTwig fails in the test phase, so the test is skipped. (How did it
pass the test before?)
WIP: slic3r: new package

Slic3r is a G-code generator for 3D printers.
perl: switch back to wxGTK (should be 2.8 for now)