graphicsframework

* Amended and added Makefiles where necessary
** Fixed/optimized Makefiles with regard to static linking
** Added install targets
* Implemented build_starsphere() in build script
* The framework part is built as a static library

Notes:
* ORC might eventually be an API (library) rather than an executable
* There are minor dependencies between the framework and the graphics implementations due to GraphicsEngineFactory
** This currently prevents the framework to become truely independent (BOINC integration)
** Plugins could be a solution to this...