Fix for crash when exiting OpenGL samples

Cause:
- Order of operations was causing the crash. The OpenGL renderer was being
  deleted before the TexturedBase skin, which depended on it.

Fix:
- skin was changed to a pointer, allowing it to be deleted before the
  OpenGL renderer.
Added newline at end of OpenGLSample
Merge pull request #29 from DeeKayHT/OpenGL_Fix

OpenGLSample crash fix