Issue #1813542 by rfay: Fixed Multipart/Alternative with line break (introduced by PEAR) breaks drupal core and results in unreadable message.

(cherry picked from commit bb257f92)

Cottser authored Jan 27, 2013 and Hans Salvisberg committed Jan 27, 2013

Issue #1417646 by Cottser, KarinG: Follow-up Fixed Cannot download Mail_Mime from SVN repo via Include module.
(cherry picked from commit f47b8cfb)

Issue #1528684 by sterndata: PHP Parse error: erroneous "$" in MailMIME::addHTMLImage() function at line 254 of file mailmine.inc

Issue #1153352: Check for existence of Mail_mimePart::encodeHeader() in mailmime_check_requirements().