first and second ring cell neighbors
first and second ring cell neighbors

Added modules to find first and second ring cell neighbors (returns cell
ids of the neighbors).
modules  added:
get_looped_cell_neighbor_list()
create_looped_cell_neighbor_list()
get_second_ring_looped_cell_neighbor_list()
create_second_ring_looped_cell_neighbor_list()

cmshobe/landlab,RondaStrauch/landlab,csherwood-usgs/landlab,ManuSchmi88/landlab,landlab/landlab,laijingtao/landlab,RondaStrauch/landlab,amandersillinois/landlab,decvalts/landlab,csherwood-usgs/landlab,decvalts/landlab,cmshobe/landlab,Carralex/landlab,landlab/landlab,ManuSchmi88/landlab,laijingtao/landlab,Carralex/landlab,SiccarPoint/landlab,cmshobe/landlab,SiccarPoint/landlab,RondaStrauch/landlab,Carralex/landlab,amandersillinois/landlab,landlab/landlab,ManuSchmi88/landlab