[bp/r48887][FIX] validation: Add a new validation rule "email_multi" for email fields that can accept multiple email addresses separated by (default) commas, and deploy on outboundEmail setting on trackers. Sadly keeping the html5 type=email attribute engages the default email validations which does not seem to be removable, so deleting that from the input field (thanks marclaporte)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/11.x@48889 b456876b-0849-0410-b77d-98878d47e9d5