Change max line length to 76

Fixes issue 13 regarding Barracuda spam filter blocking emails with
line lengths longer than 76 characters.
Resolves #14

This adds some simple logic to check for basic quoting of the email subject, and strip it out if it's being used.  RFC2047 quoting using =?charset?encoding?encoded-text?= won't be affected, but simple quoting using " characters will be stripped from email subjects.