Random coordinates interpolator given an area

[frbattid]

I'll suggest to implement the following interpotalor (in fact, nothing has to be interpolated).

Given an area (a square defined by the two vertices of a diagonal, a circle given its center and raidus...), generate random coordinates within the given area.

This could be useful when defining entities based on the count and entity_type fields. In that case, current position interpolators assume all the entities are walking the same path. Nevertheless, by using this new interpolator entities will be walking different (random) paths.