Fixes the launcher forgetting everything between runs.
Every setting on the launcher's Settings page except the three Rewind rows was reset to a built-in default on each launch and thrown away on exit, so Fullscreen, Linear filtering and the shader selection reverted every time you started the game. Window scale, Sample rate and Volume were worse than that: they were drawn, but nothing read them, so changing them did nothing at all. All of them are now saved and applied.
The ROM you pick is also remembered again. The launcher wrote its choice to rom.cfg but never read it back, so a ROM kept anywhere other than beside the game asked to be selected on every launch.
Settings are saved when you close the launcher, not only when you press Play.