introduce CSGVertex & CSGPolygon defrecords, refactor state handling in split-poly, remove obsolete mesh ctors
fix reflection warnings
refactor CSGPolygon as deftype, prepare poly bsphere handling, bugfix tangle target
add bsphere test optimization to split-poly
refactor CSGVertex as deftype
remove CSGVertex type (replaced w/ Vec3 only)
Merge branch 'feature/csg-refactor' into develop

* feature/csg-refactor:
  remove CSGVertex type (replaced w/ Vec3 only)
  refactor CSGVertex as deftype
  add bsphere test optimization to split-poly
  refactor CSGPolygon as deftype, prepare poly bsphere handling, bugfix tangle target
  fix reflection warnings
  introduce CSGVertex & CSGPolygon defrecords, refactor state handling in split-poly, remove obsolete mesh ctors
extracting/adding basic shape intersection checks from type namespaces into core.utils ns

- circle/circle
- rect/rect
- aabb/aabb
- rect/circle & aabb/sphere
bugfix aabb/scale-size
bugfix quadtree ctor & bounds impl
add intersect-sphere-sphere and add intersect-shape impl for Sphere (w/ support for test against AABB & Sphere)
bugfix meshio/read-stl to create Vec3 instances for read vertices
update octree handling in meshops ns, rename unify-vertices into canonicalize-vertices
minor update bounds impl for octree
update find-in-tree to avoid intermediate sphere object creation
bugfix intersect-sphere-sphere
add new versions of intersect-ray-triangle?, point-in-triangle2/3?, triangle-barycentric-coords to core.utils, update triangle ns
update references to migrated triangle ns fns
bugfix clockwise3?, remove obsolete fns from triangle ns
remove triangle subdiv fns (migrated to core.utils), rename t/centroid* fn