When a user signs up using any order form and the email verification is enabled, an email verification should be created and sent immediately. This verification should have a redirect that points back to the cart on the current order form.

After signup a message should be displayed if verification is enabled "An message has been sent to verify your email address. Please complete verification at your earliest convenience."

When the order is completed and the client moves to payment, two things should happen. First, the email verification record should be updated to redirect to the payment page for this order. Second, if the setting to prevent payment is enabled, and the email to be verified is the same as the contact's current email, then a message should appear on the payment page saying "Payment is unavailable until email verification is complete. To resend your verification email, click here." This link can point to ClientVerify::send(). Also we should of course actually prevent payment based on the setting and disable the payment form as well.

Add new setting to the order plugin setting "Hold unverified user orders." This setting should prevent prevent orders by unverified users from being automatically marked as accepted by the cron. A tooltip should be added saying as much.