run time shader error handling

.gitignore

include/overkill/ModelSystem.hpp

include/overkill/ShaderProgram.hpp

include/overkill/ShaderSystem.hpp

include/overkill/Util.hpp

include/overkill/gl_caller.hpp

src/EntityCamera.cpp

src/ModelSystem.cpp

src/ShaderIntrospector.cpp

src/ShaderSystem.cpp

src/Util.cpp

src/gl_caller.cpp