Rework PhysX collision flutter bug workaround

To better handle erroneous trigger events under the new timing method, use the number
of times the simulation has actually advanced instead of the number of evals received.

Cleaned up a bit.

MOULOpenSourceClientPlugin/Plasma20/Sources/Plasma/PubUtilLib/plPhysX/plSimulationMgr.cpp

@@ -355,6 +355,7 @@ plSimulationMgr::plSimulationMgr()
 	, fMaxDelta(kDefaultMaxDelta)
 	, fStepSize(kDefaultStepSize)
 	, fAccumulator(0.0f)
+	, fStepCount(0)
 	, fLOSDispatch(TRACKED_NEW plLOSDispatch())
 	, fSoundMgr(new plPhysicsSoundMgr)
 	, fLog(nil)
@@ -609,6 +610,8 @@ void plSimulationMgr::Advance(float delSecs)
 		fAccumulator = fMaxDelta;
 	}
 
+	++fStepCount;
+
 	// Perform as many whole substeps as possible saving the remainder in our accumulator.
 	int numSubSteps = (int)(fAccumulator / fStepSize + 0.000001f);
 	float delta = numSubSteps * fStepSize;