This function is indented for direct use when creating a HierarchyModifyingGroup, where this behaviour makes more sense. A "." as name of a HierarchyModifyingGroup will be the equivalent to HierarchyModifyer::hideThis.

This actually makes the implementation also easier and more efficient.

* 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