[FIX] wysiwyg: Update preview code with "improved" allowHtml detection from r46285 - fixes broken html preview, sorry & thanks Geoff

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/11.x@46371 b456876b-0849-0410-b77d-98878d47e9d5
[FIX] wysiwyg: Use refactored allowHtml code in the plugins (which depend on auto_save anyway)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/11.x@46372 b456876b-0849-0410-b77d-98878d47e9d5