Merged Unicode branch into trunk (r4952:5608). This should be fully

      backwards compatible for all practical purposes.

Fixed #2391, #2489, #2996, #3322, #3344, #3370, #3406, #3432, #3454, #3492, #3582, #3690, #3878, #3891, #3937, #4039, #4141, #4227, #4286, #4291, #4300, #4452, #4702


git-svn-id: http://code.djangoproject.com/svn/django/trunk@5609 bcc190cf-cafb-0310-a4f2-bffc1f526a37