Add particles tally

Updated and refactored the Tally class to address some shortcomings, and added more tests.
Yeah, so we went through this with nucname where we had format-specific names and then we kept changing what default format was. This meant that users and developers kept having to change their pyne-dependent code every time we changed the format.  It was a lot of extra work.  Moving to id() let us change the format without changing the usage sites. Even if we never end up changing the format, I think it is a good idea.

Also, this will make it more consistent with the other namespaces.  Someone coming to particles from nucname or rxname will know what to expect.