add scrolling bg + fix tile data

PanningCamera/background.gdshader

@@ -0,0 +1,14 @@
+shader_type canvas_item;
+
+const float y_speed = 0.5 / 3.0;
+const float x_speed = 0.1 / 3.0;
+
+void fragment() {
+	vec2 new_uv = vec2(UV.x + TIME * x_speed, UV.y + TIME * y_speed);
+	COLOR = texture(TEXTURE, new_uv);
+}
+
+//void light() {
+	// Called for every pixel for every light affecting the CanvasItem.
+	// Uncomment to replace the default light processing function with this one.
+//}