Add support for ~ to Q objects for negation

[Collin Grady <cgrady@…>]

At present there's no quick way to negate a Q object, so if you need something that .filter() and .exclude() can't do, such as Q(A) AND ((NOT Q(B) OR Q(C)), it's a bit awkward as you have to use QNot(Q(B)).

Attached patch would allow Q(A) & (~Q(B) | Q(C)) using the bitwise NOT, similar to the bitwise AND and OR already in use.

[Simon G. <dev@…>]

Interesting idea, Colin. Can you raise this on django-developers?

[Collin Grady <cgrady@…>]

added docs and tests

[miracle2k]

+1 on this.

[Malcolm Tredinnick]

(In [6518]) queryset-refactor: Added ~ support to Q-objects. Based heavily on a patch from
Collin Grady. Refs #4858.

[Malcolm Tredinnick]

Moving back to accepted so it doesn't get checked in on trunk. It's already fixed on the queryset-refactor branch.

[Malcolm Tredinnick]

(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