1) Fixed a wrong offset when extracting infill lines from the octree.
2) Added a variant for testing triangle in a bounding sphere
when buildind the octree. Currently not used as the box test
is more tight.
3) "Bridging infill" regions are now triangulated and used to densify
the octree as well to support the bridging infill correctly.
1) Octree is built directly from the triangle mesh by checking
overlap of a triangle with an octree cell. This shall produce
a tighter octree with less dense cells.
2) The same method is used for both the adaptive / support cubic infill,
where for the support cubic infill the non-overhang triangles are
ignored.
The AABB tree is no more used.
3) Optimized extraction of continuous infill lines in O(1) instead of O(n^2)
