Added OpenGLTexture class.
Added Log class.
Added a destructor to OpenGLTexture to release the texture in OpenGL.

Changed tests/render/glthrow to use QtTest.
Renamed "glthrow" test folder to state that those are tests that use OpenGL.
Fixes on OpenGLTexture.

Added constructor that takes an ID, making OpenGLTexture act as a simple wrapper
that releases the texture when destroyed.
Fixed OpenGLTexture::generate to set parameters before sending image data.
Added tests that use DevIL to generate texture data from an image.