Updated/added proper GPLv2 headers to all source files

AbstractGraphicsEngine.cpp

AbstractGraphicsEngine.h

BOINCClientAdapter.cpp

BOINCClientAdapter.h

EinsteinS5R3Adapter.cpp

EinsteinS5R3Adapter.h

GraphicsEngineFactory.cpp

GraphicsEngineFactory.h

Makefile

Resource.cpp

Resource.h

ResourceFactory.cpp

ResourceFactory.h

Starsphere.cpp

Starsphere.h

StarsphereS5R3.cpp

StarsphereS5R3.h

WindowManager.cpp

WindowManager.h

main.cpp