int add_weight(int w)
In compat mode, this function is used by the efun transfer().
An object that can contain other objects and is not a room
must define this function. It is called with the extra weight
of the object that is moved into it. If this is ok, then it
has to increment the local weight count, and return true.
Otherwise, return false, and the new object can not be entered
into this object.
The function is also called with the negative weight in the
object that the moving leaves.
Note that no set_weight() is required by the parser.
Deprecated in LDMud 3.3 as transfer() has been deprecated.
transfer(E), query_weight(A), prevent_insert(A)