If <type> is 0 this command will remove the cart from the character.
Otherwise it gives the invoking character a cart. The cart given will be
cart number <type> and will work regardless of whether the character is a
merchant class or not.
Note: the character needs to have the skill MC_PUSHCART to gain a cart

The accompanying function will return 1 if the invoking character has a cart
(any kind of cart) and 0 if they don't.

if (checkcart()) mes "But you already have a cart!";