Merge remote-tracking branch 'upstream/master' into i18n

game/engines/default/data/gfx/dark-ui/button1.png

game/engines/default/data/gfx/dark-ui/button2.png

game/engines/default/data/gfx/dark-ui/button3.png

game/engines/default/data/gfx/dark-ui/button4.png

game/engines/default/data/gfx/dark-ui/button5.png

game/engines/default/data/gfx/dark-ui/button6.png

game/engines/default/data/gfx/dark-ui/button7.png

game/engines/default/data/gfx/dark-ui/button8.png

game/engines/default/data/gfx/dark-ui/button9.png

game/engines/default/data/gfx/dark-ui/button_sel1.png

game/engines/default/data/gfx/dark-ui/button_sel2.png

game/engines/default/data/gfx/dark-ui/button_sel3.png

game/engines/default/data/gfx/dark-ui/button_sel4.png

game/engines/default/data/gfx/dark-ui/button_sel5.png

game/engines/default/data/gfx/dark-ui/button_sel6.png

game/engines/default/data/gfx/dark-ui/button_sel7.png

game/engines/default/data/gfx/dark-ui/button_sel8.png

game/engines/default/data/gfx/dark-ui/button_sel9.png

game/engines/default/data/gfx/dark-ui/mouse-down.png

game/engines/default/data/gfx/dark-ui/mouse.png