Initially align PT2 Fill textures to Top Left

Change initial Fill registration point on PT2 from Center to Top Left to align with Texture tool.

With a top-left registration point, the textures wouldn't slide under the walls if the PT2 object was expanded lower or to the right. Keep existing behavior that moving a PT2 object does not cause the texture to shift (i.e., make PT2 automatically calculate the x/y texture offsets caused by movement)