Fix - Can't work manager except utf8

#257 Manager doesn’t work with ISO-8859-1 based MODx installations any
longer
Support for encoding windows-1251 in the emails
Merge pull request #330 from olegpro/charset_issue

Support for windows-1251 encoding in emails
Update modxmailer.class.inc.php

Small fix
Merge commit '645503e407ac75064781f7ff39b7113b382d9ff3' into bugfix