- factored out 'business' code from the UI code
- moved to the new DEBUG_DECORATOR interface
- UI-less log file and log player classes as a step towards P&S unit tests
The first one keeps a log of events (start routing, mouse motion, etc).
The second allows for adding temporary debug drawings and messages which are stored synchronously with the events in LOGGER.
The event stream together with the PCB design (now with UUIDs) can be used to deterministically replay routing bugs as the user sees them.