Adding functionality to handle module messages while the module is loading

Hey Mattes,
as we discussed on Monday we have the need to handle requests for modules that are in a loading state. Therefore I added the required functionality so that these module messages are stored until the loading of the module has been finished and get then fired again.
Along the way I move refactored one or two functions regarding to their visibility and the getters first paradigm. Hope that's ok with you.

Cheers,
Stephan