Improve performance of Shader:send when the Shader is not active.

It now defers uploading the uniforms to the program object until the shader becomes active again, instead of activating the shader program and deactivating it each time Shader:send is called.

--HG--
branch : minor

src/modules/graphics/opengl/Shader.h

@@ -243,6 +243,8 @@ private:
 	// Texture unit pool for setting images
 	std::vector<TextureUnit> textureUnits;
 
+	std::vector<std::pair<const UniformInfo *, int>> pendingUniformUpdates;
+
 	bool canvasWasActive;
 	Rect lastViewport;