WIP GCode/SmoothPath.cpp,hpp cache for interpolating extrusion path with arches.
Removed Perl test t/geometry.t, replaced with C++ tests.
Refactored ExtrusionEntity and derived classes to hold extrusion attributes in new ExtrusionFlow/ExtrusionAttributes classes.
Reworked path ordering in G-code export to never copy polylines, but to work with a new "flipped" attribute.
Reworked G-code export to interpolate extrusion paths with smooth paths and to extrude those smooth paths.
New parameters: arc_fitting, arc_fitting_tolerance
Renamed GCode class to GCodeGenerator
Moved GCodeWriter.cpp/hpp to GCode/
Moved Wipe from from GCode.cpp,hpp to GCode/Wipe.cpp,hpp
Moved WipeTowerIntegration from GCode.cpp,hpp to GCode/WipeTowerIntegration.cpp,hpp
New variant of douglas_peucker() to simplify range of iterators in place.
Refactored wipe in general and wipe on perimeters / hiding seams.
WIP: Convert estimate_speed_from_extrusion_quality() and its application to smooth paths.
WIP: Cooling buffer to process G2G3, disable arc fitting for filters that cannot process it.
1) Removed virtual methods. There was not really need for them.
2) Some of the virtual methods were using conversion to Lines, which
was unnecessary and expensive.
3) Removed some nearest element search methods from Point.
after an introduction of a non-recursive variant of the algorithm.
Fixes "Strange behavior while printing curved perimeters #1503"
Fixed some compilation warnings.