Also rename command_err_badjson to generic command_err helper, since error messages aren't always about bad JSON (e.g., "command failed" for non-zero exit).
Any file in this directory which is executable and whose name only
consists of alphanumeric characters, space, '.', '-' or '_' will be
automatically loaded when lightningd starts (unless suppressed with
commandline options).
b5c300a82b