'PreferencesFormPreSave': Override preferences being saved
$formData: array of user submitted data
-$form: PreferencesForm object, also a ContextSource
+$form: HTMLForm object, also a ContextSource
$user: User object with preferences to be saved set
&$result: boolean indicating success
$oldUserOptions: array with user old options (before save)
'PreferencesGetLegend': Override the text used for the <legend> of a
preferences section.
-$form: the PreferencesForm object. This is a ContextSource as well
+$form: the HTMLForm object. This is a ContextSource as well
$key: the section name
&$legend: the legend text. Defaults to wfMessage( "prefs-$key" )->text() but may
be overridden