Introduce lifecycle events

[brunschgi]

Lifecycle events offers the possibility to listen and react on some application internals by using Connectors.
At the moment the following events are planned:

• t.register.start => emitted when application.registerModules() is started
• t.missing with params ctx, name, skins => emitted for each module that cannot be found
• t.register.end => emitted when application.registerModules() is ended

=> The above 3 could eg. be used to collect all missing modules and lazy load them on demand

• t.start => emitted when the modules are started
• t.sync => emitted when the start method of all modules has been run
• t.stop => emitted when the modules are stopped
• t.unregister.start => emitted when application.unregisterModules() is started
• t.unregister.end => emitted when application.unregisterModules() is ended