Merge utilities rips_persistence.cpp and point_cloud_edge_collapse_rips_persistence.cpp?

[mglisse]

While it makes sense to have simple examples using the Rips without cluttering them with edge collapses, and simple examples using edge collapses without too much Rips clutter, in terms of utilities, I don't really see the point in having those 2. Can't we have just one, that optionally does collapses based on the options? If the user doesn't specify, by default, we could have 1 round of collapses if min-persistence>=0 and we are computing H2 or higher (cpx-dimension>=3) and no collapses otherwise.