Problem: incremented subscriptions duplicated

[janat08]

Problem: When you define a new subscription that makes the previous one obsolete such as for infinite load and text search it's difficult to deal with if you leave the page and come back as you can't select individual subscriptions in cache. Since you'd probably want to keep the subscription that has the higher limit and yet not duplicate this same subscription or possible default the text-based one to empty on leaving the page.

Solution: make a method that returns subscription from cache with it's arguments.