rank_filter.hxx: Changed the 1D case of lineRankOrderFilter to be an enable_if case with N == 1.
rank_filter.hxx: Added lineRankOrderFilter for other dimensions.
rank_filter.hxx: Changed so that lineRankOrderFilter requires N >= 1.
test_rank_filter.cxx: Added tests for a higher dimensional case.
rank_filter.hxx: Dropped blank line.
rank_filter.hxx: MultiArray takes allocator as third template arg.
rank_filter.hxx: Dropped src_transposed_view as it is unneeded.