Add admin action to update slot names

* The slot object updates its name every time it is saved
* But sometimes its slotrooms are changed underneath it, and so the
  name can become out of date
* This method is a simple way of updating the names for all the slots

vendor/symposion/schedule/admin.py

@@ -25,12 +25,19 @@ class SlotRoomInline(admin.TabularInline):
     extra = 1
 
 
+def update_slot_names(modeladmin, request, queryset):
+    for slot in queryset:
+        slot.save()
+update_slot_names.short_description = "Update slot names"
+
+
 class SlotAdmin(admin.ModelAdmin):
     list_filter = ("day", "kind","exclusive","slotroom__room")
     list_display = ("day", "start", "end", "kind", "room_names",
                     "content_override","exclusive")
-    list_editable = ("exclusive",)
+    list_editable = ("exclusive","kind","start","end")
     inlines = [SlotRoomInline]
+    actions = [update_slot_names]
 
     def room_names(self, slot):
         return ", ".join(room.name for room in slot.rooms.all())