Added a scheme to handle mouseover and mousedown events in STATE_MENU.

- Added  DEBUG_MENU_TEXT constant that can be used to determine the position of the text in the main menu if set to true.
- Added getMenuOptionPicked(option), which is used in the previously referenced scheme. Read comment above function for description.
- Added a conditional to eventMouseDown to be used in previously references scheme.
- Removed the drawBox() as it's functions were absorbed into drawColors() a few commits ago and it was just commented out.
- Changed the following var, function, and const names for consistency:
	* MENU_HIGH_SCORES -> MENU_SCORES
	* showMenu() -> runMenu()
	* showMainMenu() -> showMenu()