AVar changes

Yesterday, i stuck AVar 0.0.4 on hackage. Again, not thinking things through as well ad i should have, i realised later it should have been the 0.1.0 release, since it was the first major change to the package since i first wrote it.

So what's new? Well, i split it up a bit, into three modules: Data.AVar, the classic interface, Data.AVar.Unsafe, the same as Data.AVar, but it throws any exceptions encountered by the variable, instead of passing them back to the user, and Data.AVar.Internal, which contains the code for the actual for AVars, and the datatypes used by them.

I think this is a nice way of doing things, and hopefully will make using the system a little easier if you don't expect to cause exceptions.

So as always, if you have any suggestions, please let me know.

-- Axman