Advanced geo to mesh mapping

Extension of the "normal" mapping of geometry on a mesh. This ensures that a geometry is mapped perfectly onto a 2D mesh (i.e. it only works with TRI & QUAD elements). The is nice to have for visualisation but will hopefully also help with simulation as it should allow a much smaller eps when looking for mesh nodes relating to a given geometric object.

What this does in detail:
* the selected geometry is duplicated (because the result may significantly change the original geometry)
* additional points are inserted in each polyline at intersections between polyline-segments and mesh-edges/nodes
* the resulting geometry is mapped via the "normal" collision detection algorithm

The functionality is also linked to GUI but does not need any GUI functionality/libraries/whatever.

Note to reviewer: It's probably best to view the files changes and not the individual commits. I did most of this with a deadline while writing a paper so commit structure and history are a bit messed up.