Portals - fix DYNAMIC particle systems
Portals - fix DYNAMIC particle systems

A regression had occurred whereby particle systems in DYNAMIC mode weren't added to the room correctly.
This PR recognise the case and bypasses the function to retrieve geometry, as retrieving the geometry is not necessary for DYNAMIC objects as they should not affect the room bound. Their AABB will be retrieved during gameplay rather than once off at level conversion.

ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot