Fixes for broadphase/paircache determinism.

Revert definition for ATTRIBUTE_ALIGNED16, and try to force sizeof(btSolverConstraint) by using unions with btScalar, for non-btScalar data types.
Use btAssert and not assert.
Don't access btAlignedObjectArray elements, for zero sets

src/BulletCollision/CollisionShapes/btBoxShape.h

@@ -179,7 +179,7 @@ public:
 			plane.setValue(btScalar(0.),btScalar(0.),btScalar(-1.),-halfExtents.z());
 			break;
 		default:
-			assert(0);
+			btAssert(0);
 		}
 	}
 
@@ -306,7 +306,7 @@ public:
 			penetrationVector.setValue(btScalar(0.),btScalar(0.),btScalar(-1.));
 			break;
 		default:
-			assert(0);
+			btAssert(0);
 		}
 	}