Changed and optimized the code for rendering the map and the player character
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main.cpp
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- Set character location variables in gameLoop() to use constants defined in userInterface.h

gameStage.h
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- Removed gameScreen() function as it waas replaced by the gameLoop() function

game.h
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- Added oldCharacterLocation variable to keep track of previous location so as to delete the previous character sprite printed, preventing a "snake".
- Used printTile() function to replace old character with character in the new location

maps.h
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- Added printTile() function to print all tiles
- Modified renderMap() to use printTile() to render the map

userInterface.h
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- Added to store UI constants and potential UI generation functions