Adding "kicad_dnp" for --show-fields creates exception in ibom.py line 166

[ckuhlmann]

The boolean field kicad_dnp (added using --show-fields kicad_dnp) creates an exception in ibom.py line 166, because it is treated as string.

Possible fix:

        for f in index_to_fields.values():
            if isinstance(f[i], str) and not f[i].isdigit() and len(f[i].strip()) > 0:  # fix by using isinstance(..., str)
                all_num = False
                break
            elif isinstance(f[i], bool): # handling of bools, please check
                all_num = False
                break