+'RenderPreferencesForm': called at the end of PreferencesForm::mainPrefsForm
+$form: the PreferencesForm
+$out: output page to render to, probably $wgOut
+
+'ResetPreferences': called at the end of PreferencesForm::resetPrefs
+$form: the PreferencesForm
+$user: the User object to load preferences from
+
+'SavePreferences': called at the end of PreferencesForm::savePreferences;
+ returning false prevents the preferences from being saved.
+$form: the PreferencesForm
+$user: the User object to save preferences to
+$message: change this to set an error message (ignored if the hook does notreturn fals)
+