[gclist] Making things manual & collectable.

[Charles Fiterman]

There is a simple way to change the collectability
of objects.

You start by making everything collectable. You
have a command gcMakeManual(void *p) which adds
p to a table. and a command gcMakeCollectable(void *p)
which removes things from the table. You might want
to have a Manual count on the table. It depends on
your usage.

Its not elegant but it works.