Switching to exponential value too soon

[Wradgio]

Hi,

We are using your library in our older project and find it very useful. Our only issue is that change to the exponential value happens too soon - 1e5 is way too soon when converting meters to millimeters (JavaScript is changing to exponential at 1e20 digits). Could it be changed to at least 1e10?

[Wradgio]

I created the pull request for this issue with only the change of exponential formatting limit to 1e10. #68