Added an SRID_CACHE to GeoDjango db/models/fields/__init__.py so that we only hit the spatial_ref_sys table once per SRID per process
Added an SRID_CACHE to GeoDjango db/models/fields/__init__.py so that we only hit the spatial_ref_sys table once per SRID per process

--HG--
extra : convert_revision : svn%3Abcc190cf-cafb-0310-a4f2-bffc1f526a37/django/trunk%4010488

Belgabor/django,Belgabor/django,Belgabor/django