Map should take a lambda?

[fabio-t]

Must investigate whether I should pass a lambda to map functions, or even better how to make it a Stream so that I can use functional-style filter/fold/map functions.

[fabio-t]

The big use case is selecting only a subset of the surrounding entities; using a filter would save a lot of code and quite possibly computation (since right now we first collect all visible entities around, and then iterate over them again to select a few).