Improved GC patch, was Re: [ nedit-Bugs-1906837 ] long list creation

[Tony Balinski]

Quoting Bert Wesarg <bert.wesarg at googlemail.com>:

> Yes, in a full reference counted scheme, we could use copy-on-write
> for the arrays, and therefore the unconditional copy for the iterator
> is a no-op if the array will not be modified inside the iteration.
>
> How far ist your refcnt patch, do you need any help?

To tell you the truth I haven't touched it for over a year! I never got as far
as running it since it required changes throughout interpret.c and macro.c. I
stopped working on it mainly because I couldn't track other changes in the
source base at the same time.

Tony