Implemented new Visitor Pattern with double dispatch.

Signed-off-by: Denis Dik <denis.dik@hs-furtwangen.de>
Merge branch 'SceneManagement' of https://github.com/FUSEEProjectTeam/Fusee into SceneManagement

Conflicts:
	src/Engine/Components/SceneManagement/ITraversalState.cs
	src/Engine/Components/SceneManagement/SceneManager.cs
	src/Engine/Components/SceneManagement/TraversalStateSearch.cs