Top down compute fix

Previously the TPRegion would only call the compute method of the actual TP if topDownMode was False. Otherwise it would assume the TP compute method had already been called and *only* do the top down compute. The CLAModel thus had to make two separate calls to TPRegion.compute.

This PR resolves this by passing topDownCompute appropriately when calling TPRegion.compute and changes the region to correctly always call the TP compute method and optionally additionally compute the top down output.