A tool to pack several images into single large image by options
GUI => https://code.google.com/p/libgdx-texturepacker-gui
Pack images => https://github.com/libgdx/libgdx
http://code.google.com/p/libgdx/wiki/TexturePacker
https://github.com/libgdx/libgdx/wiki/Texture-packer