Minor refactor: make all MatchProcessors and ActionProcessors into classes that implement an implicit interface, for clarity

Make all relative imports into absolute

- add a plugin system to easily plug external code into commands

- various fixes and improvements

Refactor RuntimeConfig to top-level module. Expand rule logic, decouple rules from mapping logic and make them act only with callbacks. Add possibility to hide prod modules with a new keyword in YAML.

Change rules: fix names for clarity and make rules operate entirely on callbacks, generalizing their implementation