Use GZIP routines for simplicity and compat
Various fixes for input handling

    * Merges input handling into one routine called thru video_sync at refresh rate
    * Adds keypad joystick calibration routine
    * Simplify joystick calibration routines to use same codepath as main emulator joystick handling
Update preferences for joystick modes

    * Preferences file changes to support a fixed joystick
    * Simplify the interface -- remove explicitly setting joy_step
Automatically save preference on quit