Added ability to play GBC games in GBA "backward compatibility mode".
Use -gba in VGB-Unix to enable GBA compatibility mode.
Use "Hardware | GameBoy Model | GameBoy Advance" in VGB-Windows.
Added ability to browse through paused replay.
During replay, press [LEFT] and [RIGHT] keys to browse.
Press [UP] to resume replay, any other key to continue.
Press any other button to continue playing.
Made replay save states approximately every 170ms.
Made replay code always return "replay-ended" when replay ended.
Made WaitJoystick() exit when window closed.