Brought High Scores Menu back in line with other menus and added some helpful functions
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main.cpp
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- Added a case for E_HIGH_SCORES

gameStage.h
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- Added option to view high scores in the main menu
- Optimized gameLoop()
- Modified victoryScreen & loseScreen() to accept any key before continuing

highscore.h
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- Added pressToContinue() to highScoreBoard()

otherHelperFunctions
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- Added flushInputBuffer() & pressToContinue()