Merge branch 'irrigation' into develop (PR #138)
This merge adds a new optional dataset of irrigation to the GEOGRID.TBL. This
dataset is 0.0833 degree (1/12 degree) resolution, about 9 km. The resulting
field, named irrigation, is a 2-d field of percentages (0 - 100).
In anticipation of other irrigation data sets becoming available, this dataset
is located under the generic directory "irrigation" and then in the data-specific
"fao" subdirectory.
The data is sourced from
http://www.fao.org/aquastat/en/geospatial-information/global-maps-irrigated-areas.
The dataset supports the new WRF model option sf_surf_irr_scheme =1, 2 and 3.
* irrigation:
change the path and interp option as default
add new irrigation dataset to table