yml file backup function added.
Stock simulator improvements. Items can now be changed.

Added 'show max stock' flag
Add maxstock to 'edit' and 'editall' commands
Display a message only when there is an update (admin users only)
Fixed an issue where help for the 'editall' command was not displayed
Fixed an error in auto-completion of the 'edit' command
StartPage editor shows a list of colors when creating decorative buttons.