Iterator

Implementation of an iterator that goes thru a Component and all its sub-components in a tree (pre-order) traversal. A test case that demonstrates the usage is also included, along with wrapping to make these iterators accessible from scripting..
The copyright block in a particular file should refer specifically to that file's code, IMO. The dates should cover the time between when the first line of this code was checked in, to the last time it was modified.

There should also be an `Authors:` line and a `Contributors:` line, especialy since the copyright line actually refers to "Authors". That should mean specifically the Authors of this file, not everyone who ever authored anything remotely associated with OpenSim. I would always include Authors and Contributors lines, even if they are blank. That gives future contributors a nice place to give themselves some credit.