Array textures can be easily drawn without a shader (resolves issue #1111).

Added love.graphics.drawLayer(texture, layerindex, …). ‘texture’ must be an array texture.
Added SpriteBatch:add/setLayer.

Added Quad:get/setLayer. This applies to array textures that are drawn without specifying an explicit layer index in the draw call.

Added love.graphics.newQuad variants which have layer arguments.

--HG--
branch : minor

src/modules/graphics/opengl/Image.cpp

@@ -92,8 +92,8 @@ void Image::init(PixelFormat fmt, int w, int h, const Settings &settings)
 	if (getMipmapCount() > 1)
 		filter.mipmap = defaultMipmapFilter;
 
+	initQuad();
 	loadVolatile();
-	initVertices();
 }
 
 void Image::generateMipmaps()