necessary changes for the latest DeviceAccess update (readAsync() return type no longer a reference, and other related changes)

- check if connections are actually working

fixed bug that using poll-type transfers in testable mode could sometimes lead to stalled tests or assert failures.

added move-assignment operators for the accessors, which is required to use move-assignment operators of modules containing accessors

Proper implementation of move constructors and move assignment operators for all module types (including tests for the assignment operator)

configuration variables are now provided to the receivers right away without any read(). Updates will never be sent.

allow obtaining the config values already before connections have been made through a speicial get() function