[Implementation] GameTimer&Related Files Updated

[Implementation NOTE]
0. Implemented CountDownTimerPausable, which has pausing ability from
android.os.CountDownTimer.
1. You can register CountDownTimerParsable to GameTimer by implementing
onTick & onFinish method.
2. GameTimer can have several CountDownTimerParsable.
3. Basically, GameTimer is controlled automatically inside AGameView.
4. But Registration to GameTimer is needed.
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p.s. Making a flag that determines infinite loop is on-going issue.
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[BUGS Found]
- ConcurrentModificationException has been found during update() of thread
- Using CopyOnWriteArrayList<E> might be a solution to this issue.
- May exist further thread-caused problems.