Before it had to be stripped for all use cases anyway, so it is better to leave it out from the beginning.

Multiplier module: add modern constructor accepting qualified path names of input, factor and output

* add HierarchyModifyingGroup

* VirtualModule: allow nested oneLevelUp etc.; simplify implementation

This is achieved by properly setting the _owner of each VirtualModule (unless highest level).

The simplification comes from then being able to use getOwner() instead of keeping track of "grandparents", and from using createAndGetSubmodule() instead of implementing something similar again in findTagAndAppendToModule().

* DataLossCounter constructor now takes qualified path to trigger variable

* Fix initial msg. Add automatic connection to the LoggingModule.

Now the Logger is a VariableGroup and in the prepare() method an empty
msg is written once. This makes sure the LoggingModule is not waiting
for initial values of Loggers and messages by other Loggers get lost.

* Add message in case on modules with Logger are found.

* Fix test and remove implementation of removed method.

* Do not use hard coded tags but use default tags.

Now all tags given to the LoggingModule are used to look for senders.

The user can now also choose to publish messages only to the control
system.

Refactored.

Reading was done only in deeper levels inside the VariableGroups.

See 1af92147. Input accessors are now properly part of the ReadAny group which improves the deterministic behaviour.

This provides a strict guarantee for the order of updates w.r.t. trigger, especially for tests.

  - Removed extra call to registerModule which caused multiple creation
    of the same module on a tree node
  - Made addChildNode private

Instead of holding the modules in a flat list as before, this represents
the ownership of nested modules correctly and prevents possible memory
access violation on destruction.

Currently does not get the modules in a way that they can be downcasted
to test if StatusMonitor, etc

Correctly navigate to parent module via virtual path.

If someone includes the Logger into an ApplcationModule and calls writeAll() the Logger variable message will be written. To catch that cases set message empty after calling sendMessage and ignore empty messages in the LoggingModule.