Flashtool deletes manually created device

[Baerbeisser]

Well yeah, my device is not supported. And i get you with requiring a fork and pull request, since creating dotzens of device files is a monotonous task. This seems abandoned too, with the last request from january but the last change from 3 years ago.

But to keep it working at all, could you make it not delete custom devices in ./devices directory and recognize them instead?