[✓][SUG] Add postview jingle music after a level ends

[Ron_Stard]

I like that NeoLemmix uses Master System music after a successful or failed level. I wonder if RetroLemmini would use them too. 

[WillLem]

Should be do-able. I'll certainly look into it.

[WillLem]

Optional postview jingles have now been added (they're off by default, and can be toggled on in settings).

The sounds are called "pass.wav" and "fail.wav" and can be found in resources/sound. They're the SEGA Master System ones by default, but can be swapped out to anything you like.

Implemented in commit 7cb734b.