samples/3D/terrainCameraDemo: Replaced aircraft with unrestricted use model
- Also referencing skycube in ModelViewer
- Model from http://www.sharecg.com/v/35513/browse/5/3D-Model/Wacky-Plane
ecere/gfx/DisplaySystem: Incrementing ref count for added textures
- Fixed new crash on exit in terrainCameraDemo