Another batch of fixes/refactorization

- Simplified transport protocol handling in the Flood FSMs.
- Flood test goal file paths are now relative to test files.
- Prefered session transports are now checked with the server output.
- Dropped `cancel_request` entirely (clients crash on failure anyway).
- Added minimal spawn interval to the Flood Manager (10 ms for now).
- Refactored Flood Server and removed some of the dead code.
Made multiple session inheritance work correctly