-added new build system "bez" - a native reference build system that allows
the user to build whatever they like in a rezbuild.py file. This is used
as a test build system for the unittest.
-added new 'bez' cli tool as part of the bez build system.
-added a unittest for the build process
-added unittest2 (unittest backport) to contribs
-reorganised test packages
-misc bugfixes