Add function to make connected sums of 4-Manifolds

[homologic]

I'm currently working on the classification triangulated 4-manifolds, and for this a function to create the connected sum of two 4-manifolds would be useful. I have tried to write this myself, however, I have trouble understanding why the puncture() function creates the two prisms and how I would generalize this to 4D or even n dimensions. Maybe I'm just too stuck in thinking about abstract simplicial complexes rather than the Delta-complexes regina uses.