Add AppConfig. Fixed overlay button position. SdlFacade partly move to Picture/GfxSdlEngine
Fix errors after sdl_facade removed.
Restore infobox for prefecture.
beautify code
Merge pull request #81 from dalerank/master

Get changes from dalerank
added taking screenshots (debug)
add dependency from boost date_time library; add date-time to screenshot filename
add libng; add saving screenshots to png
dirty fix to bug #77