only need this when generating terrain (sea = 100 - perc_land at start).
        This function forces a recount, otherwise just call the variables

def refresh_stats(self):
        """
        only need this when generating terrain (sea = 100 - perc_land at start).
        This function forces a recount, otherwise just call the variables
        """
        self.tot_pix = 0
        self.tot_sea = 0
        self.tot_land = 0
        self.tot_blocked = 0
        for row in range(self.grd.grid_height):
            for col in range(self.grd.grid_width):
                self.tot_pix += 1
                val = self.grd.get_tile(row, col)
                if val == TERRAIN_SEA: 
                    self.tot_sea += 1
                elif val == TERRAIN_LAND: 
                    self.tot_land += 1
                else:
                    self.tot_blocked += 1