[Soc2014] Official meta API

Good question!
After having worked on this API for around 5 months, I am quite convinced there is a need for an internal API. If you have a look at how much this API has evolved you can clearly see that we tried making the internals and the API match, but that simply did not work out.

That's why our public API is so generic now! and I love it this way:
1) it's very upgrade-proof
2) we let the users do the filtering, making possibilities endless and lot letting our API limit them

We could re-implement all of Django with the public API (I already tried that) but unfortunately Django does need some pre-computed parts (which are themselves calls to get_fields() + filters) to maintain the speed. We may want to change these in the future, so I suggest not to document them.

Finally, get_fields() is definitely fast for any normal use case (the internal APis depend on it). I can guarantee that ;)