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


git-svn-id: http://code.djangoproject.com/svn/django/trunk@7477 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/modeltests/ordering/models.py

@@ -48,6 +48,13 @@ __test__ = {'API_TESTS':"""
 >>> Article.objects.order_by('pub_date', '-headline')
 [<Article: Article 1>, <Article: Article 3>, <Article: Article 2>, <Article: Article 4>]
 
+# Only the last order_by has any effect (since they each override any previous
+# ordering).
+>>> Article.objects.order_by('id')
+[<Article: Article 1>, <Article: Article 2>, <Article: Article 3>, <Article: Article 4>]
+>>> Article.objects.order_by('id').order_by('-headline')
+[<Article: Article 4>, <Article: Article 3>, <Article: Article 2>, <Article: Article 1>]
+
 # Use the 'stop' part of slicing notation to limit the results.
 >>> Article.objects.order_by('headline')[:2]
 [<Article: Article 1>, <Article: Article 2>]
@@ -64,4 +71,10 @@ __test__ = {'API_TESTS':"""
 # don't know what order the output will be in.
 >>> Article.objects.order_by('?')
 [...]
+
+# Ordering can be reversed using the reverse() method on a queryset. This
+# allows you to extract things like "the last two items" (reverse and then
+# take the first two).
+>>> Article.objects.all().reverse()[:2]
+[<Article: Article 1>, <Article: Article 3>]
 """}