Fix issue #294 (really this time).

Add stencil attachment to framebuffer creation. Needed to remove depth
attachment to make it work, but that should not change anything, since depth
test is not enabled anyway. May need testing nonetheless.

src/modules/graphics/opengl/Canvas.h

@@ -77,7 +77,7 @@ namespace opengl
 		GLsizei width;
 		GLsizei height;
 		GLuint fbo;
-		GLuint depthbuffer;
+		GLuint stencilbuffer;
 		GLuint img;
 
 		vertex vertices[4];