==================
- Complete rewrite using jeffkistler and glenrobertson code
- CRS is added to GeoJSON ouput by default
- Ability to build ``pk`` dynamically by passing a lambda
- Ability to provide a ``bbox``
- Ability to use Django natural keys
- Support of *ValuesQuerySet*
- Support of *ForeignKey* and *ManyToMany*
- Added ``force2d`` option
** Backwards incompatible changes **
- Geom field is not guessed automatically : Use ``geometry_field`` option, default is ``'geom'``.
- no more ``pk`` in properties : use feature ``id``, or list ``pk`` in properties explicitly.
- ``fields`` list in ``GeoJSONLayer`` was renamed ``properties``.