[Cuis-dev] Immutability package

[ken.dickey at whidbey.com]

Ah.  Why this is important.

I forgot to say that the objects which remember the Rope/UniString state 
should also be immutable.

This means that operations on Ropes/UniStrings are thread-safe, even in 
a multi-core CPU.  All without locking.

Anyone looking at lock-free data structures and multi-core caches should 
appreciate this.

It would be really useful to be able to run milti-core, especially if 
one or more cores are GPUs. ;^)

Cheers,
-KenD