use WGS84 as default CRS for GeoJSON outputs

[vincentsarago]

ref #164

[vincentsarago]

@AndrewAnnex I'm not sure if you use the feature method but this will break the previous implementation.

That's said I'm making a minor version update because it basically follow the GeoJSON specification (coordinates should be in WGS84)

To support other geographic crs, users would need to use the geographic_crs option

[AndrewAnnex]

@vincentsarago okay responding to this one, yes I use all the capabilities of morecantile including the geojson output.

Broadly, I think since this is probably okay so long as exceptions don't get thrown preventing any non WGS84 stuff happening (warnings are good but I would want them to be opt-in for #166). As per my comment I believe however that exceptions would get thrown.

Now onto my rant for RFC7946: The spec says that although WGS84 is the assumed default, "alternative coordinate reference systems can be used..". There is no use of RFC2119 language in section 4 except for the z axis. Therefore, I think it's fine to continue producing non WGS84 geojson in this project and elsewhere, just don't force users to use WGS84 when they explicitly don't want it or implicitly don't want it by using a TMS that doesn't use WGS84.

[AndrewAnnex]

left two replies in above comments rather than view this pr review mechanism