extended the test to make sure also the "observer" variables in the control system show the right values

- implement ThreadedFanOut version with return channel
- add test for ThreadedFanOut with return channel

bidirectional variables: pass on version numbers in modules from the last blocking read on to any write operations, to resolve conflicts of concurrent variable updates properly

Implemented bidirectional process variables for control system variables. There are still bugs and the test is failing...

Added preliminary support for bidirectional variables. There are still some known issues, e.g. concurrent updates can still lead to race conditions. This will be addressed soon.

Now one can add ScalarOutput and ArrayOutput variables to the history modules by using tags.

This is still not nice. Now for every data type an individual module needs to be created.

Include descriptions of the owning Module in the descriptions of each process variable to make them more complete.

Updated to use the new ReadAnyGroup instead of the old readAny function. Some tests are still hanging or failing (mostly due to shutdown issues)

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

- check if connections are actually working