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#15 stage.dipose()를 해서 이전 스크린 stage 제거하면 listener 사라짐
Merge remote-tracking branch 'origin/HEAD' into Developer

Conflicts:
	core/src/com/mygdx/screen/MenuScreen.java
	core/src/com/mygdx/screen/OptionScreen.java
Merge branch 'master' into Developer