UFO:Alien Invasion Code

* base/textures png crush.

* crushed png files

* Reduced filesizes of the tex_nature textures folder by compressing/optimizing the files with pngout

* [TEXTURE_.MAP_RESCALE-tex_nature/railway-0.5-0.5]
* Rescaled all railway textures on all map files and prefabs (TODO:repeat this operation in data_source)
* Replaced railway texture with a 512x512 pixel version (was 256x256 before)
* Added new railway normalmap (normalmap was from the old, unlicensed file)
* updated LICENSES

* convert tga into png