Move future position calculations for built-in 2D world collision into seperate process

The current position calucation is cached and stored in live memory, but when there are many objects needing to collide and moving to positions they have not previously been in, then performance takes a major hit.

Start by locating the built-in 2D world collision code and the current cached future-position calculation. Determine how calculations are stored in live memory and how collision movement uses them; done means the calculation work runs in a separate process without changing collision behavior and addresses the reported performance hit.

Written by the indexing model from the issue text.