first upload

basic operation for the cci-fire application. At the moment is a
modified wb-sea-level application. to get the data along the frontier,
use:
cr <- crop(r.mask, extent(frontier), snap="near")
fr <- rasterize(frontier, cr)
lr <- mask(x=cr, mask=fr)
it's a crop operation, not a extract operation (see
http://gis.stackexchange.com/questions/92221/extract-raster-from-raster-
using-polygon-shapefile-in-r discussion). In this way we get a raster