Email compliant word wrapping

[Chris Beaven]

I had the case of wanting to correctly wrap text emails according to the relevant RFCs. I started by hacking django.utils.text wrap but then after some rethinking, decided to split it into a separate module (even if it is a bit of similar code).

On top of this, I refactored django.utils.text wrap method to boost it's efficiency.

[Chris Beaven]

Has tests, but needs docs.

In a nutshell, EmailMessage has a new argument:

• wrap_text -- which wraps the body text at 78 chars

At a lower level, SafeMIMEText now accepts two additional keyword arguments:

• wrap_text -- which wraps the text at 78 chars
• format_flowed -- still the format-flowed MIME parameter but assumes the text has already been wrapped

[Chris Beaven]

Regarding the django.utils.text wrap refactor, here are the results of a timeit test:

Sentence
old: 1.43731307983
new: 0.553267002106

Paragraph
old: 4.15362501144
new: 1.33707404137

10 Paragraphs
old: 17.3589639664
new: 5.5629529953

[Malcolm Tredinnick]

Please put the text wrapping refactoring in a separate ticket. They are independent and it's quite possible we'll take one (the speedup) and not the other.

[Chris Beaven]

patch devoid of the text wrap optimisation

[Chris Beaven]

Ok, separated. See also: #6668

[Alex Gaynor]

Discussion with Carl: wontfixing this, this is not demanded, easily lives outside of Django, and not particularly in scope for Django's primary use cases anyways. We'd probably still be interested in the speedups though, feel free to file a new ticket, or just commit yourself ;)