session manager startup

[ichthyo]

implement how the basic initialisation of session manager works, including initialisation of the session access mechanism.

This does not mean session startup, which happens much later.

[ichthyo]

(In #385) both tests and the corresponding entities are implemented and pass the compiler already

[ichthyo]

doesn't block the object references or the first session implementation round. There's a workaround in place for now

[ichthyo]

(In #123) future