* Add support for parsing short tons

* Extend unittest to check for short ton conversion

* Move speed parser logic into OSMValueExtractor

* Use Double.NaN for unparseable speed values

* Add a test for speedlimit "none"

* Use the same Delta for all tests

* Add tag extractor test utility

* Ignore non-positive speed values

Co-authored-by: Thomas Butz <thomas.butz@optitool.de>
Co-authored-by: Peter <graphhopper@gmx.de>