it was anyway dysfunctional and mainly slightly reducing performance.

The VoidAccessor comes along with the convenience classes VoidInput and VoidOutput,
and the TestFacility function getVoid()

Introduce StatusWithMessage and StatusWithMessageReader which handle this.
It is used in DeviceModule error reporting.
This is a preparation in order that we can report errors consistently to DOOCS, in DoocsAdapter

make StatusAggregator use StatusWithMessage

it should output always status code + string
on the input side, connects to either status or status + string
corresponding string input is found automatically
NOTE: DeviceModule API change, the status output variables are
renamed from (status, message) to (status, status_message)!

update testing of DeviceModule outputs

because of API change of DeviceModule  (renamed message ->
status_message)

fix crash and improve message and test

- fix crash due to incorrect handling of cast to Derived
- improve message output
- make existing tests pass
- add test for status message of StatusAggregator

move StatusWithMessageReaderBase and Status def to ControlSystemAdapter

since it is required from ApplicationCore as well as from the adapters

Sometimes several long running modules in a row might have caused false alarms. So seen in tests of the llrfctrl server with multiple devices (which require some time to open and initialise).

Simply add timeout to acquiring the testable mode lock and print an error message with the last thread which successfully obtained the thread. Finally throw an exception to help debugging.

to check whether stepApplication() can execute...

This generates graphviz code to visualise the connections between modules

This will print always a lot of information if one or more devices is unavailable at server start. There is a high risk that these messages distract from the actual issue (broken hardware), hence it is better to remove this.

If a circular dependency was checked and the dependent module was not
yet in the waitMap, the lock was never released.

this fixes #194

Prints a clear message if a circular dependency of initial values exists.

- All variables conceptually have an initial value now.
- All initial values read by blocking read() before starting the main loop.
- More tests failing, probably to old test exceptiations and wrong test implementations.