Validity period for custom variables

Custom variables are used a lot in SecuTix to "tag" or "qualify" a product with some custom data such as a text or a URL. custom variables can then be accessed from the SecuTix public API to display specific information attached to the product that would not be managed by SecuTix's standard catalog management features. You can now attach to a custom variable value a "start validity date" and "end validity date" t