for FDM, and "[input_filename_base].sl1" for the SLA technology.
This improves the situation of
"Filename creation with variables broken"
https://github.com/prusa3d/PrusaSlicer/issues/1918
where anything after the last dot in the file name is considered
as an extension, therefore the .gcode resp. .sl1 extension is not added.
Now the user gets the output_filename_format filled in with the correct
extension.
Also now if the output_filename_format is empty, the output name
is generated anyway.
from the current Model/ModelObjects.
Fixed a possible race condition in updating Print::m_placeholder_parser
with the proposed filename / filename base.
Improved documentation (source code comments).
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.
