Fix T36804: the property sensor when set to interval was causing a memory leak

The property sensor was using CValue::FindIdentifier(), which does an AddRef(). However,
the property sensor was not calling Release() when it was done with the value. This could
cause more leaks when used in conjunction with the copy property actuator since it would
really throw off ref counts.

source/gameengine/GameLogic/SCA_PropertySensor.cpp

@@ -207,6 +207,7 @@ bool	SCA_PropertySensor::CheckPropertyCondition()
 
 				result = (min <= val) && (val <= max);
 			}
+			orgprop->Release();
 
 		break;
 		}