Integration of reusing by inheritance and by delegation

Namespaces

namespaces UndoRedoManager::ByDelegation and UndoRedoManager::ByInheritance with common files in UndoRedoManager

Tests

For UndoRedoStack, Manager and CompositeCommand

Specification via Tests

This is the base for a C++ workshop to develop an undo redo framework. the specification is done via tests.