[✓][SUG] Prioritise exits over other objects | [DISC] Lemmini bit handling

[WillLem]

OWWs ... are always written into physics as-is; they are unaffected by this update.

Well, as it turns out, OWWs themselves weren't included in the list of trigger types that bypass the new hierarchy check. The updated physics only allows a single gadget trigger per-pixel for certain types, allowing us to decide which to prioritise; OWWs were supposed to be able to bypass this because (a) they have no effect on other gadgets, and (b) overlapping them creates vertical-destruction-only terrain, which is known to be used in a handful of Lemmini levels.

The affected levels are few and far between though, and the chances of this bug being discovered this soon are extremely slim. However, thanks to ericderkovits' diligent replay testing, it's been spotted and I've been able to ensure that OWWs are (once again) allowed to overlap.

The oversight is down to another OWW-related variable being included in the check originally (specifically, the check for OWW-allowed-terrain) having been moved over from the original procedure in an effort to preserve current special-case handling; I was simply unaware that this variable didn't refer to OWW gadgets themselves. The more you know.

Anyway, it's good and fixed for 2.2, which will be released in due course.