wip: case-insensitive destinations

nav.py

@@ -69,7 +69,7 @@ def main():
         for key in sorted(ROUTES):
             print(f"{key:12} {NAMES[key]}")
         return
-    destination = sys.argv[1]
+    destination = sys.argv[1].lower(
     if destination not in ROUTES:
         known = ", ".join(sorted(ROUTES))
         sys.exit(f"Unknown destination: {destination} (known: {known})")