UFO:Alien Invasion Code

* base/textures png crush.

* crushed png files

* A few more crashed UFO textures

* Recompressed all textures in base/textures/tex_ufo with Trimage image compressor and commited those files, where a filesize reduction of at least 5% (up to 81.5%) was achieved

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

* updated textures by MCR

* convert jpg into png