Update #11 (build 61) — CaesarIA Steam update #1520945

Hi guys. This update is huge, but don't get too excited - it's much more on the back-end than on the front-end. Massive work was done to the game code: * Game graphics engine were rewritten, textures batching is now used to lower GPU usage; * Compiled with SDL2/mixer libs, thus 3rd-party modules dependency is avoided and the size of other used libs is reduced; * Appended OpenGLES2 (mobile devices/Android) renderer for textures batching mode. After that, of course, fixes and new textures: - Fixed a crash while displaying routes on the global map; - Fixed Library/Academy construction process; - Fixed soundtrack playback on Linux; - Fixed rendering of tiles, which are placed on the edges of the map; - Fixed a crash during a briefing between missions, when there is no available missions to continue; - Fixed special orders window for barn/warehouse, free space is now used properly; - Fixed ci...