Performance Improvements

[karl2883]

Two performance improvements:

• add a ContainsEntity function that checks if an entity container contains an entity without allocations. Using GetEntities().Contains() as before allocates a new List each time, which is costly in hot paths
• Rewrite the Collide.Check IL hook to only check for EeveeHelper relationships if the entities would actually collide - in an ordinary level, the amount of collision checks that fail because there is no collision should be vastly greater than the ones that fail because there is an EeveeHelper relationship, so this is cheaper.