use a different work around for the thread_local problem: moving the code using the thread_local specifier to the cc file also solved the problem and does not require a complicated work around using a map...

- Added tag "MicroDAQ.CONFIG" to all configuration variables, to make it easier to publish only them into the control system

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

Changed an exception into an assert, since the function is only internally used and the exception is never thrown. Clafiried the documentation about this.

- check if connections are actually working

removed incorrect implementation of operator[] and operator() in ApplicationModule (and use the implementations of ModuleImpl instead)