Restrict Checkout Until Email is Verified in WooCommerce

The code in this plugin prevents checkout until the customers email address is verified. Checkout page notices are displayed based on several different scenarios :

Logged in users with verified email can proceed to checkout
Logged out users with verified email will be served a notice to login before checkout is enabled
Logged out customers using billing email addresses not registered will be served with a notice : You need to register a new account and verify your email address before completing checkout.
Logged in or out users who’s accounts are not verified will be served a notice : Your email is not yet verified. Please verify your email before proceeding with the checkout. Resend Verification Email

Plugin Settings

Settings enable you to :

Customize the verification email subject line and body
Set the number of expiration days before the user account is deleted
Enable the checkout restrict conditions

Admin & My Account

Both the WordPress users table and WooCommerce my account page for logged in customers have been extended which include :

Custom columns added to the WordPress users table for email verification. A resend email verification button is displayed if the account has not yet been verified. Once verified, the button is replaced with verified text.
A resend email verification button added to the My Account page for WooCommerce customers.