Put a strong reference from a JSEventListener to its wrapper.

This should fix #54.
Replace EGL code with Qt code in the GraphicsSurface
Implementet copyToGLTexture with a shader.
Use a new painter and paint device for each paint
Ensure that the gl commands are processed after painting
Use the same gl context for all the gl drawing
Do not create an EGLImage for video rendering
Fix texture creation for the tile buffers
Don't destroy anything when surface is used for video playback
Release framebuffer used for shader copy