Symbol map fixes

Load/save the symbol map properly, add a setting to do it automatically.  Moved it to Core/System since it's already in sceKernelModule and it kinda makes more sense there anyhow.

Also fixes emulation -> stop to go back to the menu, which was kinda related since it didn't seem like quitting saved the symbol map reliably.

I've grown quite fond of symbol files now.

-[Unknown]