enable routing tool without selection, and support multi-select

website/src/locales/en.json

@@ -94,8 +94,7 @@
                 "tooltip": "Return to the starting point by the same route"
             },
             "start_loop_here": "Start loop here",
-            "help_no_file": "Select a file item to use the routing tool, or create a new file from the menu.",
-            "help_multiple_files": "Select a single file item to use the routing tool.",
+            "help_no_file": "Select a file item to use the routing tool, or click on the map to start creating a new route.",
             "help": "Click on the map to add a new anchor point, or drag existing ones to change the route.",
             "activities": {
                 "bike": "Bike",