Define collision_type and split up orthogonal collision method a bit more
Also outsource construction of local coordinate system
Small fix
Translate construct_local_coordiante_system() into C++
Translate collision-type detection into C++
Abstract collision_quadrant_type
Cosmetics
Translate situation-specific collision-handling into C++ - WIP

This is work in progress.

The rootfinder routine for the EDGE_HITS_EDGE case has to be
partly rewritten yet.