Added write_esri_ascii function.
Added write_esri_ascii function.

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