Add a few missing switches to -help
SDL: Handle 5200's START as console button
SDL: Don't rely on 1270 version of sdl12-compat
Add Atari 5200 BBSB! alternative mapping
Add support for J(atari)Carts & DCart
Remove SHIFT and/or CONTROL modifiers for 5200
SDL: Don't reset SHIFT/CONTROL
SDL: Make HELP key work with SHIFT/CONTROL