Solve error with rgeos::createSPComment()

[aleruete]

I noticed that the main error was with createSPComment() while creating the sp SpatialPolygons. I changed mainly dg_process_polydata() to work with sf and convert to sp Spatial later.

polydata  <- lapply(polydata, function(x) {
                                              x["seqnum"] <- NULL
                                              x <- rbind(x, x[1,])
                                              x <- list(as.matrix(x))
                                              x
                                            }
                      )
  polydata  <- st_sfc(lapply(polydata, st_polygon),
                          crs = st_crs(4326))

  polydata  <- as_Spatial(polydata, IDs = an) 

I had to repeat the first point of each cell to be able to close the grid cells. x <- rbind(x, x[1,])

I also corrected the license NOTE.

I still get some other NOTEs on the package size but only that

[r-barnes]

@aleruete - Is this still an issue in the latest version? If so, please rebase and reopen.