* Laid foundations for SpatiaLite support in `GeoQuerySet`, `GeoWhereNode` and the tests.
* Added the `Collect` aggregate for PostGIS (still needs tests).
* Oracle now goes to 11.
* The backend-specific `SpatialRefSys` and `GeometryColumns` models are now attributes of `SpatialBackend`.
* Renamed `GeometryField` attributes to be public that were private (e.g., `_srid` -> `srid` and `_geom` -> `geom_type`).
* Renamed `create_test_db` to `create_test_spatial_db`.
* Removed the legacy classes `GeoMixin` and `GeoQ`.
* Removed evil `\` from spatial backend fields.
* Moved shapefile data from `tests/layermap` to `tests/data`.

Fixed #9794.  Refs #9686.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@10197 bcc190cf-cafb-0310-a4f2-bffc1f526a37