Generate most distant starting point

Add starting point as a most distant from the map center. This should allow random starting position.
This probably should be new filter DistantStart

Start by locating the existing starting-point selection and map-center logic, then inspect how map filters are defined. The issue proposes a DistantStart filter that selects a starting point farthest from the map center and enables random starting positions; done means that behavior is implemented and covered by the project’s relevant tests.

Written by the indexing model from the issue text.