moved group read/write and []/() oprerators from the VariableGroup class into the Module class, to make the functionality also available in ApplicationModules

Changed Module::connectTo() to accept also temporary module objects, e.g. as returned by findTag(). As a consequence, the operators [] and () of the modules had to be changed to const.

fixed poll-type inputs using no longer non-blocking read after the switch to the NDRegisterAccessorBridge-based accessors

Rebased the ScalarAccessor and ArrayAccessor classes onto the mtca4u::NDRegisterAccessorBridge class.
Known problems present: code compiles but tests do not run