Engine: * Lowered Birdy's vertical acceleration while increasing his horizontal acceleration * End turn after Birdy disappears * Added English and German locale strings for birdy * Reordered weapon menu

foreach(dir "Fonts" "Forts" "Graphics" "Locale" "Maps" "Music" "Sounds" "Themes" "Missions" "Names")
  add_subdirectory(${dir})
endforeach(dir)