Rationalize jQuery dialog usage

Previous submission used a true modal dialog. This caused problems when the content in the dialog box itself opened a dialog e.g CKEditor. 

A non-modal dialog is now created (same as current - mea culpa) but with improved sequencing when there are multiple dialogs open and the overlay is clicked to close (last opened - first closed etc.)

new functions:
displayDialog() - responsible for creating and closing dialogs.
modalConfirm() - a replacement for the native javascript confirm() - usage: modalConfirm(title,text).then(function (reply) {...};

modified functions
modalDialog(), helpDialog() & modalNotes  - each is called in a different way but they
each create a div with a title & html and then call displayDialog()

helpDialog also uses JSON to call help_text.php (only one call now)