Adding missing OPENGL_LIBRARIES for openglsupport test. Also adding OpenGL include directories as a better pratice even though these are system include directories in most systems.
Added cmake uninstall target.
This adds a cmake command make uninstall
Running make uninstall removes the files installed by running make install
Workaround various "returning reference to temporary" warnings.
Merged in infinitei/eigen-opengl-fixes (pull request #90)

Adding missing OPENGL_LIBRARIES for openglsupport test.
Merged in infinitei/eigen (pull request #91)

Added cmake uninstall target