-) Scoping functions are not handled generally
-) Added evaluate_for_subcategories function
-) Added debug_cart and debug_products and debug_values variables

Signed-off-by: Reinhold Kainhofer <reinhold@kainhofer.com>

Version 4.0: Fix globals warning; Add Values_Debug variable; Add contains_any/contains_all functions

The shunting yard algorithm had to be severely extended (by using a temporary operand stack for the function arguments, and by storing the type of the previous token to distinguish unary operators from binary)