add ability to unset compass when coords field is empty

init.lua

@@ -340,6 +340,10 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
         local coords = coords_from_string(fields.coords)
         if coords then
             set_compass_meta_pos(meta, coords)
+        elseif fields.coords == "" then
+	    -- assume player wants to reset compass
+	    meta:set_string("waypoint_compass:position", "") -- TODO make unset()?
+	    -- TODO reset label too? or keep it to be safe?
 	end
 
         local label = fields.label