Add {sitename}, {membership_end}, and {membership_start} to all emails

It would be handy if all the above tags are added to all Subscriber and Admin emails, particularly to Renew email.

Adding {sitename} will allow to add site name in front of any relative URL while subscription_start and subscriptionend tags will allow to let Member and Admin both know when membership started and ending in various emails, particularly in Renew email that the subscriber will keep as a proof of renewal.

Thanks