Added player & ghost interaction & fixed bugs
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bullet.h
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- Fixed the bug where shooting at the wall beside the wall will cause an error

character.h
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- Added Pacman::isHitByGhost() to handle Pacman-Ghost collision
- Added Ghost
	- isAlive() to handle Ghost death
	- Modified move() to handle situations where there is only 1 way out

game.h
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- Fixed the bug where shooting at the wall beside the wall will cause an error
- Fixed the bug where shooting a bullet will cause the player to flicker
- Added code to handle Ghost death
- Added code to handle Player death

maps.h
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- Added a function to compare 2 Directions and check if they are opposite (Eg. LEFT is opposite of RIGHT)