Fixes #68

Implemented first part of #17: A HierarchyModifier can now be specified instead of the eliminateHierarchy boolean flag. No new functionality is yet added.

Use one file per class. Also, use boost::core::demangle instead of
checking for abi::__cxa_demangle by ourselves.

We have a visitor now for generating
 - the XML
 - the Module's dot graph
 - the textual dump of the VariableNetwork
 - the dot graph of the VariableNetwork

Proper implementation of move constructors and move assignment operators for all module types (including tests for the assignment operator)

fixed connectTo() so it now uses the dynamic/virtual model and thus obeys e.g. eliminated hierarchies etc.

- removed the no-longer-necessary optional argument of findTag() - use flatten() instead

This reverts commit 7287c4b4.

revert last commit, cascading ApplicationModules should be avoided instead (and should be prevented in future)

- allow setting the "eliminateHierarchy" flag in the constructor of a module

This is an interface change which was done in an incompatible way!

added function to flatten teh hierarchy, renamed eliminateHierarchy() into setEliminateHierarchy() for better clarity

added preliminary support for tags to application variables which can be searched for and used to generate virtual modules

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

added function to obtain list of accessors from modules recursively (i.e. including accessors from sub-modules)