It would be good if there was a warning about deleting roms

[matijaerceg]

just ran an export to my mister for the first time. I just made one test folder in the plan, and added a single game, and hit export to mister to see how it might interfere with my existing roms from update_all. Unfortunately, it deleted all the existing arcade roms/folders on my MiSTer. I didn't realize that it wasn't set to the 'speed' setting by default, and had (stupidly) assumed it was because the screenshot in the readme shows that. In any case, might be good to throw up a warning or two if the export that's about to take place is destructive to give first timers a heads up :)

[city41]

Ah yeah, sorry about that. I'll add some kind of warning for this. Or maybe just default to speed?

[matijaerceg]

Another option is to tell people not to use it in conjunction with update_all, but for arcade cores, to use it instead of update_all. And then, also add a bit more to the documentation how to go about 'converting' one's mister setup from existing update_all to ammister. I'd be happy to not use update_all for arcade stuff, but only ammister, since it does better organization, as I'm sure some others would as well.