Added UNUSED macro to libslic3r.h, used it to reduce some compile warnings.
Split the Int128 class from Clipper library to a separate file,
extended Int128 with intrinsic types wherever possible for performance,
added new geometric predicates.
Added a draft of new FillRectilinear3, which should reduce overfill near the perimeters in the future.
Added an "overlap" member variable to fill classes in the preparation
for futher move of the "infill / perimeter" overlap to the Fill class.
Moved the orientation predicates from Fill to Geometry.
Initial implementation of the "infill link maximum distance" feature.
Parts of the perimeter connecting two infill lines will be dropped,
if longer than a given threshold.
