[Amibe] TriangleHelper.reverseProject to Splitter.getReverseSplitPoint

getReverseSplitPoint do not supposed that the 4 points are in the same
plane, which happen when using a too high merge point tolerancex
[Amibe] BeamInsertion: rm collapsed edges from the kdree before collapse
[Amibe] EdgeCollapser: bug fix
[Amibe] more explicit assert message