Also important for upcoming mega commit...

Will be important for a mega-commit I'm preparing.

Can possibly avoid a lot of debugging pain.

Found via `codespell -q 3 -S ./tools -L splitted`

scas, it's not needed any more.

This will allow interesting override scenarios, adding flexibility.

Also, remove zasm/test7 because it changes too much all time time
(whenever zasm changes) and isn't precise enough. Too much noise,
not worth it.

For now, only a dummy app, but it's emulated properly with libz80.
Exciting times!