Feature parity with official SNES VC

[beta215]

It would be interesting to add the three main features of the SNES official Virtual Console into blargSNES:

• An in-game button combo to switch from first player controller to second player controller.

• Add an option to display the screen in pixel perfect mode and in 4:3 aspect ratio at the same time, giving sharpness and the right aspect ratio.

• If possible, implementing save states.

• Optional: implementing a GUI for the bottom screen like the official one, so you can resume the game, save a state, load a state, reset the game and/or open 'blargSNES config', all just by a single touch on the bottom screen. And also, making a message screen for the bottom screen while in-game, like the official one, that indicates something like 'Touch here to open blargSNES options', so you can pause the game and check the bottom screen options.