CB Paid Subscriptions

Given the check is already there it would seam easier to just extend it to only check if they've at least 1 active exclusive top level plan. This would just be a matter of adding 1 more option to the existing parameter. Shouldn't be too complicated to implement, but enableFreeRegisteredUser check probably should be extracted to a function since it's checked in about a dozen spots. This can be in addition to Option 2 in a future release, which should just be a simple dropdown to select required plans below "Allow Free Registered Users (without subscriptions)" when set to the new option. Example as follows.

Allow Free Registered Users (without subscriptions): No
Plans Required for Registered Users: Any | Exclusive Plans | Specific Plans
Specific Plans Required for Registered Users: SELECT_LIST_OF_PLANS

CBSubs allows multiple exclusive subscriptions, grouped by parent plan. So can also be used among child plans.

The problem with this is if you've a dozen non-exclusive addons that are not unique to a parent plan you then have to duplicate those plans to every single parent plan as child plans and if they change parent plans they lose that addon plan. It's just not an acceptable solution for global non-exclusive addon plans.

I have now reviewed all locations, and actually, it looks like it's doable by changes only in class `cbpaidUserRegistration` around `enableFreeRegisteredUser` uses.

Thus another idea that I actually like even better than "1" and "2", let's name it "4":

4. Subscription plans get a new setting, in Workflows tab, CB Login workflows fieldset: Allow login (default ON).

This setting would be available only if `enableFreeRegisteredUser` is not ON at general config,

A user wanting to disable logins with certain plans just switches this to OFF.

Advantage: No mixup with Exclusive, or different Exclusive settings, and maximum flexibility.

Thoughts ?