A mistyped --emulator exited 0 with no profile found, and a correct one
with no gaps was left out of its own report, totalled across all
emulators. The name is now checked, the emulator always printed, and
--list-emulators added for the suggestion to point at.
slots ended a mistyped --platform on a traceback; generate_truth,
refresh_data_dirs and auto_fetch exited 0 having done nothing for it.
All six now stop on require_platform before any work.
The declared-names test now builds its own platform: Batocera files the BK under elektronika-bk since its slug map was completed, so the real data no longer shows two ids for one name.
Abdessamad Derraz