basic stuff for loading map data

src/c3nav/mapdata/apps.py

@@ -1,4 +1,19 @@
 from django.apps import AppConfig
+from django.conf import settings
+from django.core.checks import Warning, register
+
+from . import mapmanager
+
+
+@register()
+def has_map_data_check(app_configs, **kwargs):
+    if not settings.MAP_DIRS:
+        return [Warning(
+            'There are no map data directories configured.',
+            hint='Add mapdirs=/path/to/directory to your c3nav.cfg.',
+            id='mapdata.W001',
+        )]
+    return []
 
 
 class MapdataConfig(AppConfig):
@@ -6,4 +21,5 @@ class MapdataConfig(AppConfig):
     verbose_name = 'map data manager'
 
     def ready(self):
-        pass
+        for map_dir in settings.MAP_DIRS:
+            mapmanager.add_map_dir(map_dir)