settings: also hide "debug.setextraloglevel" when logging is set in advancedsettings.xml
settings: "masterlock.lockcode" is an action setting and not a string setting
settings: fix ISettingsHandler::OnSettingsSaved() definition

This fixes profile settings not being saved when when normal settings are saved
and prevents the Master lockcode from being saved to profiles.xml after it has
been changed in Settings -> System -> Master lock.