matching: option to configure tolerable time differences

With some realtime data sources (such as some HAFAS endpoints) and some GTFS datasets, there are minor discrepancies between the realtime data and the plan data, e.g. 1m for a departure of a specific trip.

We could introduce an option to allow such time differences when matching.

• In the respective SQL queries, the time range would have to include the tolerance.
• There should be logic in JS that fails if there are >1 matches, because in these cases, the matching can be wrong.

as reported by @hbruch