New EventDispatcher and major refactoring.

engine-core.py

guru.py

modules/base/exceptions.py

modules/base/mail.py

modules/cli/padavan.py

modules/communication/liquidsoap/playerclient.py

modules/communication/redis/adapter.py

modules/communication/redis/messenger.py

modules/communication/redis/statestore.py

modules/core/engine.py

modules/core/events.py

modules/core/startup.py

modules/core/state.py

modules/database/model.py

modules/liquidsoap/__init__.py

modules/liquidsoap/helpers/__init__.py

modules/plugins/api.py

modules/plugins/monitor.py

modules/scheduling/calendar.py

modules/scheduling/fallback_manager.py