Added function to check if the requesting account has permission to access the cart...

Added function to check if the requesting account has permission to access the cart and if cart should be assigned to the account.
Fixed incorrect "ID" (should be "id") in updateTimeEntryCounts() in regCartSupport.
Removed some unwanted fields in several data classes and added pointer entries to get frequently used data.
Updated cart and checkout links and other layout issues for registrations.