formalise bootstrap phases

[plastikfan]

this is a continuation of issue #22

Identified phases are:

• go init: features register handler with message bus using go init functions
• build: factories/builders run. The director uses DI to resolve dependencies, navigator is created at the end of this phase and is initialised
• intercept: resume can register its hibernation filter with the navigator
• feature init: feature handlers are invoked
• pre-launch: navigator send OnBegin event
• launch-phase: navigation proceeds

So the navigator can be created and intialised independent of features. The navigator can will expose an interface for use by features. Some navigator properties should not be readily available, eg the ability to intercept filters as requred by hibernation should only be avilable to hibernation feature, therefore the navigator can expose another interface with an intercept method that can be queried for.

Feature can if they require hook into life cycle events.

[plastikfan]

Just been watcing a video (Solid programming - No Thanks) by the Primeagen discussing SOLID and he mentioned (during the discussion about Dependency Inversion Principe) a convention in Go where when writing methods/functions, you should receive interfaces but return structs. Something to think about.