Changes

• Fix mupen64plus-core URL in the about dialog
• Fix GLideN64 not showing native path seperator in the configuration dialog (see gonetz/GLideN64#2860)
• Add 'SDL controller mode' option to the options dialog of RMG-Input
• Add 'None' option to configuration file of mupen64plus-input-gca (thank you @GhostlyDark)
• Update GLideN64, mupen64plus-core and SDL_GameControllerDB