Added "known" as a valid model file type
   => 'Known files (*.stl, *.obj, *.amf)|*.stl;*.STL;*.obj;*.OBJ;*.amf;*.AMF;*.xml;*.XML',

When dialog pops up, it can see ALL known file types instead of only stl.
Respect perimeter/infill order when multiple extruders are configured but only one is used
Allow drag and drop for OBJ files
Fix memory leak in avoid_crossing_perimeters. #1044
Merge pull request #1059 from cakeller98/Universal_File_Visibility

Added "known" as a valid model file type
Lower 0.5*w to 0.4*w to fill finer gaps. #1057
Remove scale from G-code comments
Allow custom ranges with layer_height = 0
Remove cooling checkbox from simple mode
Safer safety_offset() for ExPolygons
Removed offset() method from Slic3r::Polygon because it only works with ccw polygons
Bugfix: solid-infill-below-area wasn't ignored when fill_density = 0, causing solid layers here and there. #1049
Replace SetValue with ChangeValue to avoid wxWidgets to fire useless events
Refactoring: use the clone() method for inflating Surface objects
Bugfix: infill direction wasn't correctly alternated when infilling every 2 layers. #1068
Better bridge direction detection. #1068
Bugfix: support material and brim didn't work correctly. Includes unit test. #1074
Launch even if config is corrupted. #1067
Don't crash at the end of empty prints. #1042
better handling of too-small and too-short models #929.
These changes handle small models better in the plater preview.
Extremely small thumbnails are preserved instead of culled,
allowing the model to be scaled up. The scale range is extended to
100000% to allow mm-scale objects expressed in meters to be opened
and scaled to mm.
Original coding by mesheldrake