Unique Identifiers

Hey all,

I added unique identifiers to the Avogadro Molecule class. This means
that each Atom and Bond will get a unique identifier. So, if you are
going to be wanting to hold on to a pointer to an atom, instead you are
better off holding on the to the id (unsigned long) that is given to the

I didn’t do residues yet because I have nothing to test yet but they are
done just as easy. There are a few hacks I had to do to make it work OK
but as far as I can see it works great. Drawing with undo/redo is
fantastic. The only thing I see is a problem with the auto-valence
stuff which I just haven’t had time to sit down and debug. The main
problems are done and maybe someone with more “know how” on that stuff
could handle it. I’m not sure.

Anyways, please test this out but I think it’s ready for release.

PS: It requires an update to the latest OB trunk.