Restrict coordinate precision to prevent floating-point rounding errors

[dhimmel]

Here are some coordinates from runs.geojson:

[6.584877799999998,  45.2505965,         2723.1],
[6.5850034000000015, 45.250722300000014, 2727.72]

Note that floating point error is causing false precision. It looks like it might be possible to round or truncate these numbers at the max precision available in the source data and save some space in the materialized output.

Specifically, 45.250722300000014 could become 45.2507223.

I'm also joining coordinates across runs, so would have a bit more confidence in the veracity of that operation without the polymorphic precision.

[dhimmel]

Not sure if this code is related:

https://github.com/russellporter/openskidata-processor/blob/e6f1663fff0eff722df2e393c722b137b2912e2c/src/io/OSMToGeoJSONConverter.ts#L122-L123

[russellporter]

Makes sense! I think the referenced code is on the input side, maybe we need to do some rounding on the output side. Not too sure where the code is anymore..