[common.float_cmp] refactor, fixes #27, refs #26
[common.float_cmp] refactor, fixes #27, refs #26

This is complete rewrite of FloatCmp. There is a new compare style, numpy,
which is now also the default. Calling DSC::FloatCmp::id works for scalars
and all combinations of vectors that specialize VectorAbstraction (see
previsou commit).

renemilk/DUNE-Stuff,renemilk/DUNE-Stuff,renemilk/DUNE-Stuff