Improve the name simplification algorithm

[JonasAlaif]

The current algorithm will create confusing names in the case of a clash. For example given the two names box_123 and box_222 it will simplify these to b and bo - it is unclear which of these corresponds to 123 and which to 222. The updated algorithm is more symmetric in that it finds the least common prefix required to differentiate between these two, in the example this would be box_1 and box_2.