Enable Coupons for Extras, Renewals, and Upgrades

Expand coupons to be able to be used in all situations for maximum promotional flexibility to increase total customer checkout value.

Plugin users are losing out on revenue opportunities due to the inflexibility of the coupon system.

Coupons should have switches to enabled or disable use for extras, upgrades and renewals.

This will provide greater success to users who will stay in business and continue to use the plugin.