implement new django-based models and loadmappkg command

src/c3nav/mapdata/management/commands/loadmappkgs.py

@@ -0,0 +1,19 @@
+from django.core.management.base import BaseCommand, CommandError
+from django.db import transaction
+from ...packageio import MapPackagesIO
+
+
+class Command(BaseCommand):
+    help = 'Load the given map packages into the database'
+
+    def add_arguments(self, parser):
+        parser.add_argument('mappkgdir', nargs='+', type=str, help='map package directories')
+        parser.add_argument('-y', action='store_const', const=True, default=False,
+                            help='don\'t ask for confirmation')
+
+    def handle(self, *args, **options):
+        with transaction.atomic():
+            MapPackagesIO(options['mappkgdir']).update_to_db()
+            print()
+            if input('Confirm (y/N): ') != 'y':
+                raise CommandError('Aborted.')