UFO:Alien Invasion Code

* base/textures png crush.

* Recompressed all textures in base/textures/tex_nature with Trimage image compressor and commited those files, where a filesize reduction of at least 5% (up to 66.3%) was achieved

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

* [TEXTURE_.MAP_RESCALE-tex_nature/rock008-0.25-0.25]
* Rescaled all rock008 textures on all map files and prefabs (TODO:repeat this operation in data_source)
* Replaced unlicensed rock008.jpg texture with a selfmade 1024x1024 pixel version (was 256x256 before)
* Added optimized, new rock008 normalmap
* Updated LICENSES

* added normalmaps for all tex_nature/desert* textures