Add keyboard shortcut for toggling warp mode

[Dirk Hoffmann]

There should be a menu item (with an associated shortcut) for toggling warp mode. Right now, the small hourglass icon in the status bar has to be pressed. Sometimes this becomes annoying because the mouse needs to be released before the icon can be clicked.

FSUAE uses Cmd-W for this purpose. Unfortunately, this combination is the standard key combination for closing the front window on a Mac.

[Dirk Hoffmann]

Finally, I've found a solution I personally like. The CapsLock key can be bound to warp mode.

When enabled, vAmiga runs in warp mode as long as CapsLock is hold down.