dma:   1. Implemented image_dense_subrect and image_is_dense for SplitLayout   2. Fix a bug in GenericLayoutIterator::continuous_steps()
dma:
  1. Implemented image_dense_subrect and image_is_dense for SplitLayout
  2. Fix a bug in GenericLayoutIterator::continuous_steps()

StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion