Use 17 digits of precision with Double.ToString

[oleks]

Using 15 digits ("R") leads to failure of roundtrip serialization/deserialization.

See also https://learn.microsoft.com/en-us/dotnet/api/system.double.tostring

Another example is 0.6822871999174

[oleks]

I suppose one could make the argument that it is better to parameterize the library by the format that it should use for Double.ToString, since G17 is also broken, just in a different way.

Serialize(Deserialize<float>("1.1")) != "1.1"

Hence, it is probably best to let the users choose their poison.