Add more filters

[brakenwagen]

The current offering of filters is very limited is there any plans to expand the number of filtering options with things like hq3x, xBRZ, SuperEgle, an lcd shader or crt shader ect?

[YoshiRulz]

The only thing vaguely "planned" is to switch the user-provided shader option from RetroArch's old format to its new one (#4198).