sort imports using isort. tested.

core/admin.py

@@ -1,14 +1,18 @@
 import django.forms as forms
 from django.contrib import admin
+from django.core import serializers
 from django.forms import ModelForm
 from django.http import HttpResponse
-from django.core import serializers
 
+from troggle.core.models.caves import (QM, Area, Cave, CaveAndEntrance,
+                                       Entrance, LogbookEntry, PersonTrip)
+from troggle.core.models.survex import (DrawingFile, SingleScan, SurvexBlock,
+                                        SurvexDirectory, SurvexFile,
+                                        SurvexPersonRole, SurvexStation,
+                                        Wallet)
+from troggle.core.models.troggle import (DataIssue, Expedition, Person,
+                                         PersonExpedition)
 from troggle.core.views.other import exportlogbook
-from troggle.core.models.troggle import Person, PersonExpedition, Expedition, DataIssue
-from troggle.core.models.caves import Cave, Area, Entrance, CaveAndEntrance, LogbookEntry, PersonTrip, QM
-from troggle.core.models.survex import SurvexBlock, SurvexFile, SurvexPersonRole, SurvexStation, SurvexDirectory
-from troggle.core.models.survex import Wallet, SingleScan, DrawingFile
 
 '''This code significantly adds to the capabilities of the Django Management control panel for Troggle data.
 In particular, it enables JSON export of any data with 'export_as_json'