Moved messageWindow init to lazy load on first keyWindow call. Aleviates _messageWindow loading below the sharedApplication keyWindow.
Moved messageWindow init to lazy load on first keyWindow call. Aleviates _messageWindow loading below the sharedApplication keyWindow.

xueqiu/TWMessageBarManager,CharlyInc/TWMessageBarManager,zuojx1013/TWMessageBarManager,primoz990/TWMessageBarManager,VojtaStavik/TWMessageBarManager,AlexanderMazaletskiy/TWMessageBarManager,howeguo/TWMessageBarManager,cooksimo/TWMessageBarManager,ben181231/TWMessageBarManager,hbucius/TWMessageBarManager,bobqian1130/TWMessageBarManager,terryworona/TWMessageBarManager,revile/TWMessageBarManager