Unnecessary quotes added to email addresses in CiviMail mailings

An extra set of quotes are added to the name portion of email addresses in the "To" and "From" fields of the mail headers during CiviMail mailings.

The contents of the header fields end up as follows: "\"John Smith\"" <jsmith@email.com>
The proper format should simply be: "John Smith" <jsmith@email.com>

The extra set of quotes are unnecessary and in fact cause problems in some email readers.

The quotes are added in CRM/Mailing/BAO/Mailing.php. The fix is to first check if the name field already contains quotes and not add the additional quotes if it's already quoted. This applies when setting $verp['reply'] (line 885), $headers['From'] (line 910), and $recipient (line 1054)