Preliminary work for tree-based nets

Minimum spanning tree for small nets
Still not satisfactory, since B2B is much weaker and will interact badly
Less naive MST executing in O(n² log n) + cleanup

Still suboptimal, but should be sufficient for our use
Cleaner main for both MST and B2B
Merge branch 'master' into MST

Performance regression for upper bound because of MST calculation
Micro-optimizations on the algorithms
Some cleanup
Merge branch 'master' into MST
Updated FindCOLOQUINTE.cmake file
Merge branch 'MST'

This branch provides a better main as well as minimum spanning trees.
The interface is unmodified.
Everything I have to do is listed