Adds an alpha-stage prototype: FastQuery
FastQuery enables the use of .values querysets, to bypass the overhead involved with marshalling Django models. This is implemented via a queryset-compatible API, to attempt to make the distinction between model-based querysets and dictionary-based querysets invisible to the serialization layer.
This version also brings some improvements around caching of Fields.
These changes are undocumented and untested, and should be treated as unstable. They can only be used by opting into them: for FastQuery, this means using the FastDynamicFilterBackend; for fields caching, this means setting the ENABLE_FIELDS_CACHE setting to True and setting a class variable (ENABLE_FIELDS_CACHE as well) on individual serializers.