Removed StringMap
Use Pointf for origin_translation and pass const refs whenever possible
Don't transfer ownership of Model to Print::Object
Fix clear_objects() and clear_volumes()
Turn ExtrusionLoop into a collection of polylines. Includes some changes to the Polygon API to avoid returning newly allocatd objects
New semantics for ExtrusionLoop objects. Early processing of perimeter overhangs for paralellizing such work and making G-code export lighter. Lots of refactoring. This should fix a number of minor bugs, including reversals of perimeter overhangs.
Merge branch 'sapir-modelcpp'
Several minor fixes to Model
Replace to_SV_ref() and to_SV_clone_ref() with templated glue functions
Remove new/delete keywords from ClipperUtils.cpp
Merge branch 'master' into printcpp

Conflicts:
	lib/Slic3r/Print.pm
	lib/Slic3r/Print/Object.pm
	xs/lib/Slic3r/XS.pm