Add support for prefetching fields
This makes it possible to specify the fields that should be
prefetched as part of a getForFields query. Doing a prefetch on a
ReferenceProperty when it is known that the property will be
referenced in (almost all) entities is far more efficient than
doing the invididual fetches sequentially.
# Getting the normal admin routines, classes, and `site` instance.
from django.contrib.admin import autodiscover, site, StackedInline, TabularInline, HORIZONTAL, VERTICAL
# Geographic admin options classes and widgets.
from django.contrib.gis.admin.options import GeoModelAdmin
from django.contrib.gis.admin.widgets import OpenLayersWidget
try:
from django.contrib.gis.admin.options import OSMGeoAdmin
HAS_OSM = True
except ImportError:
HAS_OSM = False