[DGD] implementation of function pointers

[Felix A. Croes]

The 'function' type is implemented using DGD's builtin type framework,
as a special kind of light-weight object.  The following two declarations
are equivalent:

    function foo;
    object "/builtin/function" bar;

These special light-weight objects don't define any functions themselves
(though as with normal objects, non-existing functions can be called
in them without error).  Furthermore, /builtin/function cannot be
inherited from.  The sole purpose of these objects is to provide the
function datatype.

Regards,
Felix Croes