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.

It can be static and it may make sense to use it outside modules. The implementation should probably move to a Application member function to make it easier to reach from non-module code.

to check whether stepApplication() can execute...

This was a left-over from times when no proper initial value propagation
and exception handling was implemented in ApplicationCore. Waiting until
the backends are open is anyway not sufficient, since the DeviceModule
needs to finish the recovery procedure. If any test would still rely on
this (anti-)feature, it would be subject to race conditions.

The wait is removed because it prevents important tests for the
exception handling specification. In particular, tests which
intentionally break devices during startup of the application would not
be implementable.

When writing special modules (e.g. the MicroDAQ module) it may be necessary to both override and call this function explicitly.

This generates graphviz code to visualise the connections between modules

Require e.g. when needing to report an exception programmatically

The previous implementation using the mutex had two issues:

1. The mutex was locked in a different thread than unlocked (DeviceModule constructor vs. handleException() thread). This results in undefined behaviour.
2. The boost::shared_mutex::lock_shared() function is not an interruption point, so applications did not terminate while waiting for initial values. (boost::latch::wait() is an interruption point.)

Just use enableDebugDataLoss() to enable debug output.

- testCircularDependencyFaultyFlags now uses modern AC without defining CS module and overriding defineConnections()

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Circular dependency detection: Outputs which are pogrammatically set to faulty are treated like external inputs.

- Implemented but not tested yet
- All existing tests passing

* Not implemented yet. Currently always return false.
* Test exists and compiles, but is failing due to the missing implementation.