improve lattice refinements
known bugs / things that need to be done
-
throw an error if the refinement is applied to a non-triangular tiling -
after the refinement, polygon indices are set to zero -
think about neighbour search; simple radius search fails -
update neighbour graph on the fly during the construction of the refinement would be the most elegant way -
use geodesic distances for the cuts, rather than Euklidean