[Need help] Make Feature#properties generic

[guizmaii]

It compiles but I'm unfortunately not able to make tests pass.
I don't know how to manage the case where GeoJson can be GeoJson[C] and in the same time GeoJson[C, P]. My Scala skill stops here 😕

[muuki88]

Thanks for taking the time to improve this library 😃

Not the tests, but the test compilation fails. I spotted two
issues

1. No format found: to read/write your new generic property type P you need an implicit format in scope, which seems not to be the case
2. Diverging implicit expansion: the Scala compiler has problems finding a single applicable Format instance.

I'm currently on mobile. Hopefully I find some time to checkout your code a give some more help.