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/Canvas.cpp

@@ -140,7 +140,7 @@ Canvas::Canvas(const Settings &settings)
 
 	this->format = getSizedFormat(settings.format);
 
-	initVertices();
+	initQuad();
 	loadVolatile();
 
 	if (status != GL_FRAMEBUFFER_COMPLETE)