Extend utils/dump-stl.pl to also write STL files
Failing test case about spurious infill in hollow objects, caused by shells being correctly generated even for hollow objects - however sometimes we don't want that
Proper fix for preventing shells to propagate too much
Fix test description
Smarter handling of hollow prints. Optimization included
Make sure there are no gaps in spiral vase. Includes regression test. #1251
Add spiral vase test for hollow models
Merge branch 'master' into new-support2