UFO:Alien Invasion Code

* Reduced filesize of the tex_buildings textures folder by compressing/optimizing the .png files with pngout

* [TEXTURE_.MAP_RESCALE-tex_buildings/floor019-0.5-0.5]
* Rescaled all floor019 textures on all map files and prefabs (TODO:repeat this operation in data_source)
* Replaced unlicensed floor019.jpg texture with a 256x256 pixel png version (was 128x128 before), based on Nexuiz source file
* Added new floor019 normalmap, added missing floor018 texture and normalmap, based on source files from Nexuiz
* Updated LICENSES