Easier way to validate karaokes database
Right now when people are submitting new karaokes to karaokemugen/karaokebase, they have to go through an entire database generation, which can take a while on some systems.
To speed up this process, we could stop generation just before it starts writing into the database.
A command line argument like
--validate, and/or a link in the admin section (cc @bcourtine) could be useful to launch karaoke folder validation and rewriting (in case of new karaokes needing a KID and audio gain data generated)