Major update. Changes to StartMenu, OptionsPage, HelpPage, GameLoop, new Application class, new global (GL) attributes in globals.py, new EXIT_GAME function.  (1)-Added new class, Application, an instance of which is created and then called instead of StartMenu; this class holds an outer while loop for the application.  (2)-Application creates a single instance of StartMenu, OptionsPage, and HelpPage; entering one of these pages simply calls the appropriate already-created instance of the page. That is, only one instance of each of these classes is created while the game is run (which improves over previous logic).  (3)-In contrast to these Page classes, no instance of GameLoop is saved within Application to be subsequently accessed.  Instead, every time a new game starts, a new instance of GameLoop is created and subsequently called.  (4)-Several self attributes of GameLoop are now objects at the module level of globals.py which is imported as GL (i.e. import globals as GL).  Specifically, self.screen -> GL.SCREEN, self.clock -> GL.CLOCK, self.fps -> GL.FPS.  Note: self.surface was removed as it was equivalent to self.screen, which is now replaced by GL.SCREEN.  (5)-Some setup code at top of main.py moved to globals.py.  (6)-Some setup code within GameLoop.__init__ moved to globals.py.  (7)-New NEXT_PAGE attribute in globals.py, access as GL.NEXT_PAGE.  (8)-New EXIT_GAME function in globals.py.
Fixed merge conflicts.
Merge branch 'mk13-master'
Minor code formatting.
(1)-Mapped all inputs for my gamepad, for both 'D' and 'X' input types.  (2)-Moved Input class to globals.  (3)-Added INPUT1 and INPUT2 to global namespace, access via GL.INPUT1 and GL.INPUT2.  (4)-Tweaked Player class appropriately to handle changes to input.
Changes to input handling.  ESC from HelpPage or OptionsPage or GameLoop returns user to StartMenu; ESC from StartMenu exits the game entirely.
Significant changes made to Input class and overall input handling.   Directional pad now works on my (Brian) gamepad.  Select button on gamepad now has same functionality as ESC key; start button has same functionality as Enter key.
Changed input handling so that the only input that can be received during a paused game is the input to un-pause the game (i.e. enter key or start button).
Resync upstream while keeping my changes