Standalone packs for Sega consoles: Game Gear, Genesis, SMS.

[hotelvictorcharlie]

This is along the same lines as #846.

I think there are many benefits to creating standalone packs for these Sega consoles, because they are supported by many devices (such as various EverDrives, MiSTer, Nt Mini, and Analogue Pocket).

SG-1000 has already been split out into a standalone pack, and I think we should do the same thing with these other consoles for similar reasons. Right now we have a Master EverDrive pack which includes Sega SG-1000 via a placeholder. And we have other packs that include Master EverDrive as a placeholder, which creates two levels of nesting. While some devices that support SMS roms also support SG-1000 roms, some (such as the EverDrive GG and Mega EverDrive) do not, and others (such as the Analogue Pocket, which I want to make a pack for) expect the SG-1000 roms to live outside the parent SMS directory. Therefore, I think we should get rid of the placeholders that point to Master EverDrive because not all devices support the nested placeholders that it references (and even on the ones that do, sometimes they want those files to be in a different location).

The same is also true of the other consoles. For example, the EverDrive GG supports SMS roms, but right now our EverDrive GG pack doesn't contain any. So we want to add a placeholder. But the device does not support SG-1000 roms. So we should have a placeholder in the EverDrive GG pack that can point to a Master System pack, but not the SG-1000 pack. This PR fixes that.

And while the Mega EverDrive supports 32X roms, the devices that refer to the Mega EverDrive pack via placeholders (Genesis_MiSTer, Nt Mini Noir) do not, so it doesn't make much sense for us to be referencing them from other packs designed for devices that can't run them.

Also, this solves a lot of the existing duplication between the Master EverDrive and Analogue Nt Mini packs, and fixes the problem of them getting out of sync (for example, this update from 4 months ago still hasn't been applied to the SMS roms inside the Nt Mini packs).

[tjanas]

I am against this change.

Also keep in mind, Master System is not a simple drop-in for Analogue Nt Mini; it specifically requires some files to be renamed with specific file extensions to indicate specific mappers. Ideally, both Nt Mini consoles would receive new JB firmware updates to eliminate this dependency so that the same set of filenames could be used across the board, which would then permit a drop-in for Nt Mini.

I don't think there should be both a "Master EverDrive SMDB" and "Master System SMDB". They are logically the same device targeting the same hardware target.

I would like to hear thoughts from @SmokeMonsterPacks @frederic-mahe on this before making any major changes like this.

[hotelvictorcharlie]

Also keep in mind, Master System is not a simple drop-in for Analogue Nt Mini; it specifically requires some files to be renamed with specific file extensions to indicate specific mappers. Ideally, both Nt Mini consoles would receive new JB firmware updates to eliminate this dependency so that the same set of filenames could be used across the board, which would then permit a drop-in for Nt Mini.

I don't know if we'll ever get a firmware update to fix that, but 97.5% of the roms in the Nt Mini packs' SMS directories have an .sms or .sg extension. Perhaps we could simply move the few outliers into an "NT Fixed" directory (like we do with Atari 2600 and NES)?

I don't think there should be both a "Master EverDrive SMDB" and "Master System SMDB". They are logically the same device targeting the same hardware target.

Except they aren't, because we are trying to use this one pack to support several different devices, each of which either does or doesn't support SG-1000.

[hotelvictorcharlie]

I don't know if we'll ever get a firmware update to fix that, but 97.5% of the roms in the Nt Mini packs' SMS directories have an .sms or .sg extension. Perhaps we could simply move the few outliers into an "NT Fixed" directory (like we do with Atari 2600 and NES)?

I just added this in 29d666e.