Improve OpenStreetMap data

[Tristramg]

This ticket is a tracking of data quality encountered with OSM data and how we fixed them. This is focused on the French railway based on the tag ref:FR:SNCF_Reseau

• Discontinuities (detected by the builder functions): often a bridge/tunnel hasn’t the tag. Sometimes it’s part of the track that has been removed
• Missing tag: must be fixed by hand by comparing with the OpenData
• Bad tag: sometimes it’s a typo
• 0's at the begining of the ref (fixed by trying with or without initial 0)
• The tag changed: we’re not really sure why, but the meters in the tag slightly change sometimes (we are more tollerant)
• The ref tag is sometimes missing: must be added (mostly in smaller junctions)