Add coordination number flag.

[frozzare]

We need a flag on the ::Valid method making it possible to turn of validation for coordination number (+60 on day). The flag should default to enabling them as that is how it is currently working.

See personnummer/meta#9 for meta discussion.

[arbitur]

Just out of curiosity, why would someone want to disable "samordningsnummer"?

[frozzare]

@arbitur not sure why.. personnummer/python#5

[arbitur]

That issue was created by someone not aware of what samordningsnummer is, I'd say it worked as intended for him. I vote against adding this flag.

[frozzare]

Maybe, but it may be case where you want to disable this and we have a spec to follow for all implementations (see meta repo). It's not a big thing.

[arbitur]

Oh, I wasn't aware of the meta repo. I guess it's already settled then 👍

[arbitur]

I see now that I complettely missed you linked to meta.....