Restrict Content Pro 3.5.45

Improvement: Change the label "Membership Level" -> "Membership" in the exporting tools.
Fix: Error when the setting "Remove Data on Uninstall" was enable. There was a wrong file reference.
Update: Misc Setting label "Multiple Free Subscriptions" to "Switch Free Subscription" since it makes more sense.
Add: Missing settings in the System Info Page(Stripe Statement Descriptor, Stripe Statement Suffix, Remove Data on Uninstall, Switch Free Subscription).

Fix: Remove forcing the usage of attributes `userlevel` or `level` in shortcode `[restrict]`. The `[restrict]` shortcode will be deprecated in future releases.

Improvement: Style Stripe information box.
Improvement: Update codebase to have sync RCP with RC Free.
Feature: Allow shortcode [restrict] to use levels as number in attribute `userlevel`.