Version number / unique ID
For ROOT data structure version, would like to use a unique ID rather than relying on morons (e.g. Rogers) to update ClassDef macro. Propose implement a bunch of macros that define the version number as an integer. This should also be reachable through Globals, PyGlobals. Additionally require test to do a comparison of the version number in README file and check that it is the same as the version number in PyGlobals.