Add tolltip and popup options to map layer configuration.

- `tooltip` takes the name of a GeoJSON property that will be
  shown in a tooltip when hovering the mouse over a feature.

- `popup` can take either the name of a property as above, or
  the boolean value `true`. In the latter case, a table of all
  the feature's properties will be shown when clicking on the
  feature. In the former case, only the value of the designated
  property will be shown.

bin/import_map_layers.py

@@ -56,16 +56,31 @@ if __name__ == '__main__':
 			file_info = {
 				"type": "map_layer",
 				"format": layer["format"],
-				"name": layer_name
+				"name": layer_name,
+				"tooltip": layer.get("tooltip"),
+				"popup": layer.get("popup")
 			}
 
 			db.save_file_data(logical_filepath, json.dumps(file_info))
 
 		else:
 			file_info = db.get_file_data(logical_filepath)
-			if file_info and file_info["name"] != layer_name:
+			dirty = False
+			if file_info:
+				if file_info["name"] != layer_name:
 					print("Renaming to", layer_name)
 					file_info["name"] = layer_name
+					dirty = True
+				if file_info.get("tooltip") != layer.get("tooltip"):
+					print("Changing tooltip to", layer.get("tooltip") or "null")
+					file_info["tooltip"] = layer.get("tooltip")
+					dirty = True
+				if file_info.get("popup") != layer.get("popup"):
+					print("Changing popup to", layer.get("popup") or "null")
+					file_info["popup"] = layer.get("popup")
+					dirty = True
+
+			if dirty:
 				db.save_file_data(logical_filepath, json.dumps(file_info))
 			else:
 				print("Already in DB")