框架keyDown事件机制微调，重构框架主循环和控件相关代码

可以用键盘和手柄控制光标（手柄不完善）
整理代码和部分语言文件细节

parts/scenes/app_arithmetic.lua

@@ -229,7 +229,7 @@ scene.widgetList={
     WIDGET.newKey{name='7',x=540,y=320,w=90,font=60,fText="7",code=pressKey'7'},
     WIDGET.newKey{name='8',x=640,y=320,w=90,font=60,fText="8",code=pressKey'8'},
     WIDGET.newKey{name='9',x=740,y=320,w=90,font=60,fText="9",code=pressKey'9'},
-    WIDGET.newButton{name='back',x=1200,y=660,w=110,h=60,font=60,fText=CHAR.icon.back,code=pressKey'escape'},
+    WIDGET.newButton{name='back',x=1200,y=660,w=110,h=60,font=60,fText=CHAR.icon.back,code=backScene},
 }
 
 return scene