Fixed include path in gridfinity test file.

Updated images and readme.

Merge branch 'elliotf-makerbeam-extrusions'

Merge branch 'elliotf-mellow-fly-d5'

Merge branch 'pcremades-master'

Added links in the project readme to STL, DXF and SVG files.

Added simple Gridfinity generator and examples.

Merge branch 'schiele-corexy_fix'

Merge branch 'pcremades-master'

Added pose_stl() module because pose() only works for assembly views.

Merge branch 'trnila-barrel_jack_cutout'