template. Reworked naming of the plater exports to not use the output file name template, but to derive the file name from the first printable object's name. Fixed error handling: Reimpemented the Perl's "eval" blocks as try / catch blocks.
still PrintObject::_slice_volumes() needs some love to set the PrintObject matrices correctly.
The XS was left only for the unit / integration tests, and it links libslic3r only. No wxWidgets are allowed to be used from Perl starting from now.