Support for config.json

[mattwigway]

This looks for a config.json file in the network folder, and if it finds one, deserializes it as a TransportNetworkConfig object and uses that in creating the street network. This enables changing the traversalPermissionLabeler.

This is a draft because there are a number of other config fields that are not currently supported by r5r:

• Adding R5 network modifications to the config file (currently handled in R5 TransportNetworkCache, not used in R5R)
• Setting the inRoutingFareCalculator (though R5R has its own way of doing this).

I'm kind of inclined to just check for these unsupported features and give an error if the user attempts to use any of them, while allowing use of the other config features.

[alexmgns]

Hi @mattwigway,

Tests on master weren't passing earlier. Could you please merge master to your branch so that the tests can run properly.

[rafapereirabr]

@mattwigway , is there some documentation somewhere about what changes can be done through the config.json file ?

[mattwigway]

Not really. I was leaving this in draft until conveyal/r5#974 is reviewed, because these changes don't do much interesting without that