Cart-to-do

the changes we need to apply to put the cart into normal sale mode are:

  *  enable guest checkout
  *  enable existing customer accounts
  *  enable new account creation

These changes require the following actions:

  *  enable guest checkout    . . . select one radio button under Settings -> Stores -> ASI Store -> Options and save
  *  enable existing customer accounts    . . . execute one SQL statement at MYSQL command line interface
  *  enable new account creation    . . . remove a symlink and copy a file in Opencart's 'catalog/controller/{account, checkout}' directories (two symlinks total, and two files)