Copied django.forms to django.oldforms and changed all code to reference django.oldforms instead of django.forms. Updated docs/forms.txt to add 'Forwards-compatibility' section that says you should not be using django.oldforms for any new projects.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4208 bcc190cf-cafb-0310-a4f2-bffc1f526a37