Limit by contact for all organisms

Contact Limit now adds a new possibility to support the following request:

"The event Romeo & Juliet is available for sales on cross sales channels of different Organizations. I want to add a limit that for one Contact, he can only purchase up to 5 tickets for this event on all sales channel of different organizations"

The Contact limit configuration adds a small improvement: the sales channel selection is no longer mandatory, having it blank means the limit applies for all Sales channel.