red-brick/npw: Move more logic into MandatoryLineEditChecker
red-brick/npw: Improve collision handling for auto-generated identifiers
red-brick/npw: Reorder ListWidgetEditor buttons

Also preserve original items and be able to restore the original state.
red-brick/npw: Add working directory and language options
red-brick/npw: Remove duplicates from working directory combo box

Also disable inserting for working directory combo box.
red-brick/npw: Add environment editor to arguments page