CRM-4868 CiviCRM Html e-mail function doesn't work as it should

Change Utils/Mail.php to send out html messages correctly if the $html_message variable is passed in (currently it almost works...)

Instead of :

$headers['Content-Type'] = 'text/plain; charset=utf-8';

Should Be:

if ($html_message)

{ $headers['Content-Type'] = 'multipart/mixed; charset=utf-8'; }

else

{ $headers['Content-Type'] = 'text/plain; charset=utf-8'; }

Per forum http://forum.civicrm.org/index.php/topic,9170.0.html it would be good if this could be extended a bit more - just so much that if people put a htmlReceiptMessage.tpl file in place then it would pick it up. This would give people an option in the meantime & hopefully be compatible with some future more significant work in this area.