Added doctest for np.intp.
Added doctest for np.intp.

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