Bug in email.txt documentation example code

[Simon Willison]

The header injection example code in ​http://code.djangoproject.com/browser/django/trunk/docs/email.txt only checxs for '\n' in the headers, but Django itself checks for '\r' instead. Suggestion: instead of throwing a ValueError in the SafeMIMEText class throw a "BadHeaderError" (or similarly named) that is a subclass of ValueError. The example code can then try to send the email and show an error if it catches that exception.

[Adrian Holovaty]

(In [1798]) Fixed #1139 -- Changed django.core.mail to raise BadHeaderError (a subclass of ValueError) and changed docs/email.txt example to use that