[libretro] added core options for inverting MD Mouse Y-axis (needed by Populous II) & showing lightgun crosshair
[Gamecube/Wii] fixed more bugs in cheats menu
[Gamecube/Wii] increased GUI list scrolling speed
[Gamecube/Wii] fixed arrow buttons in Cheats Menu
[Gamecube/Wii] added configurable BIOS & Lock-on ROM support
Merge https://github.com/ekeeke/Genesis-Plus-GX