Prepare the 'objectlib' package to be separated into a library module
Refactoring: split the 'objects' package into two, 'objects' and 'objectlib'.The point: we're going to need to move the 'objectlib' stuff into its own library module, and that's because we're going to create a new app module which needs access to it.
Rename some classes.
Progress making the Solver state more abstract.