Refactor SystemCore to be Scenegraph Independent
in the current implementation the SystemCore depends on OpenSG as for example the threading is implemented using OpenSG threads. In order to use a different scenegraph implementation (e.g. OpenSceneGraph) these library specific types needs to be extracted.There are different ways to realize this:
- use boost for threading, locking,...
- write a wrapper around the OpenSG specific classes, which can also be implemented e.g. using OpenSceneGraphs OpenThreads and decide during compile-time which implementation should be used
- like b but this time, decide at runtime (i.e. during initialization)