Reduce sample load memory and startup time

If you are working with large sample libraries or if you use an old computer, you can turn on lazy loading in SuperDirt as mentionned here.

Instead of loading all your audio samples in the RAM as usual, SuperDirt will load audio samples on request. This is better for people working with a limited amount of memory.

To enable it, update SuperDirt to the last commit (go into the downloaded-quarks/SuperDirt folder then git pull) then, in the SuperDirt startup code, before any ~dirt.loadSoundFiles call, put a ~dirt.doNotReadYet = true;.