Updated UI w/ re-constructed Main Menu, and Preference Page

Main Menu looks similar to existing, but is re-written to be programmatically generated which should hopefully keep it simpler to maintain.  The Multi-player buttons are currently disabled.  

Implements a PreferencesViewer which implements sliders for SFX Vol, Music Vol, Screen Size and test buttons for SFX and Music.

Implements a PreferencesModel which holds volume levels and screen sizes.

Implements a PreferencesController which receives interrupts from PreferencesViewer to update PreferencesModel and has stubs

Added a tank_icon for upper-left corner of windows

TODO: 
1) Add code to play test sounds when the volume test buttons are pressed
2) Add the Save Preferences stuff
3) Need to add the code for handling controls, but now that the framework is in place it should be straight-forward.
4) Add tank icon for task tray