select_related() implicit joins

I've attached a patch. It needs unittests and should be tested with trunk.

unit tests

fixed two minor bugs

get_cached_row had a slipup

The patches provided didn't actually filter my related objects, as_recurse_fields was never saved when cloned and fields= wasn't supplied to the functions. I added a patch with that.

Thanks for doing this. I had rolled my own for this, but it wasn't nearly as clean.

clones and uses _recurse_fields

Haven't heard from Malcolm about it yet.

(In [6899]) queryset-refactor: Allow specifying of specific relations to follow in select_related(). Refs #5020.

Promoting to accepted: if it's fixed in the queryset refactor then it has obviously an accepted issue.

(In [7477]) Merged the queryset-refactor branch into trunk.

This is a big internal change, but mostly backwards compatible with existing code. Also adds a couple of new features.

Fixed #245, #1050, #1656, #1801, #2076, #2091, #2150, #2253, #2306, #2400, #2430, #2482, #2496, #2676, #2737, #2874, #2902, #2939, #3037, #3141, #3288, #3440, #3592, #3739, #4088, #4260, #4289, #4306, #4358, #4464, #4510, #4858, #5012, #5020, #5261, #5295, #5321, #5324, #5325, #5555, #5707, #5796, #5817, #5987, #6018, #6074, #6088, #6154, #6177, #6180, #6203, #6658