Add support for mapper 515

Is it possible to add NES 2.0 mapper 515 on Nestopia.
iNES 2.0 Mapper 515 is used for 패밀리 노래방 Family Noraebang, a Korean karaoke cartridge that uses UNROM-style PRG banking, has provisions for an expansion cartridge, an ADC for Microphone input, and a clone of the Yamaha YM2413 chip for expansion audio: the K-663A.

https://drive.google.com/file/d/1IuIZrcW-Fno57Pzhc5FmC6aGaYS68JGj/view?usp=drivesdk

[carmiker]

Yes, it is entirely possible to add this mapper. I will add it to my list. I have recently added microphone input for Karaoke Studio and the FDS microphone, using a real physical microphone, to Nestopia JG, so this mapper could be one more thing that supports an emulated microphone through a physical microphone. The code for the YM2413 is more or less done in the Konami VRC7 code already, and if all else fails, I have a nice clean YM2413 implementation in one of my other emulators, Cega.