More SDL_NewThread fixes
Fixed the copyright notice in OECgShader
Load an additional row of items to prevent pop-in
Implements synchronous screenshots in OEGameView:

* -screenshot returns a screenshot of the game view as shown on the screen: filter if any, and size depending on the window size;
* -nativeScreenshot returns a screenshot of the game view as rendered by the core: no filter, and native size.
Update mupen core from hg