Added feature to change colour of HUD elements
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game.h
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- render()
	- Modified to accept an OptionSet as a parameter to obtain the colour of the HUD to render
	- Modified functions called to use the OptionSet passed
- levelLoop() & customLevelLoop()
	- Modified to process new parameters in OptionSet for HUD colours

gameStage.h
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- Modified some functions to call printControls()
- Modified optionsMenu() to be able to change the new HUD colours

options.h
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- Added an enum BG_COLOR
- Struct OptionSet
	- Added a COLOR hudTextColour and BG_COLOR hudBGColor
	- Modified constructor to initialize these variables
- Added a function getBGColour to set return the colour id of a particular colour named by BG_COLOR
- Modified saveOptions() & loadOptions() to work with new HUD settings