hid/gtk: Focus file save dialog at exit to "Save", not "Close without saving".

Avoids inadvertently loosing work when closing the application. "Cancel" would
also be a safe choice of default focus, but the choice of "Save" is copied from
gedit to help give better platform consistency on Gnome systems.
png: add explicit round() calls to the scaling

After this commit the tests pass on both 32- and 64-bit builds.
Hopefully this time it's really dead; the previous "fix" af27c2d
by myself merely increased the DPI of the output, but this one
attempts to get deterministic rounding behaviour.

Tests from folks with actual 32-bit machines are welcome.

Closes-bug: lp-860037
polygon.c: Readability cleanup for frac_circle()
Fix some broken assumptions regarding 32-bit integer coordinates in polygon1.c
Adding the OpenSCAD exporter to configure.ac

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Adding the OpenSCAD exporter to src/Makefile.am
Adding the hid.conf file of the OpenSCAD exporter.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Adding the OpenSCAD exporter.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Added a default GPLv2+ license text to the OpenSCAD 3D-model file.

Changed and improved some comments in between 3D-model code to
allow for better human readability and understanding what happens
where.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Added the pcb copyright notice.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Correction of a copy-paste leftover in the OpenSCAD 3D-model file license.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Determine the package type based on the modelname and add this information to the 3D-model output file.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Remove fp suffix.

Test for the occurrence of an accidental ".fp" suffix in the
modelname string and remove this suffix from the modelname string.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Include the packages container include file in the exporter output.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Correction in comment.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Correction in indentation.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Added openscad_get_basename().

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Added doxygen comments for documenting the code.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Added openscad_get_dirname().

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Added an entry for an include directory.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>