Arrays are not GC'd

[quoll]

Arrays were merged with the known issue that they are not made available for CG.

That said, the "mark" function does identify arrays, and ensures that anything in a reachable array will be marked to prevent collection of those elements. Just need to mark arrays themselves, and unset those arrays that are not in use.

[quoll]

Have this done. Needs proper testing. More importantly, we need to address #36 before I'll consider closing this issue.