add version conformance (#163)

[tomkralidis]

Addresses #162.

[chris-little]

Looks good. (Automated numbering of section swould be good too ;-)

[chris-little]

@jonblower Are you happy to merge this PR163 to address Issue #162 ?

[jonblower]

@chris-little @tomkralidis I have no objection in principle to the idea. But before we do anything, I think we'll need to sort out this repo to create a tag for the final version 1.0.0, and establish that future PRs will be targeting version 1.1 (and maintain a changelog). Also we'd need to update the schema.

Would this be a compulsory property from version 1.1 onwards? Maybe it should be optional to maintain backward compatibility? I assume it would apply to all CoverageJSON documents?

[tomkralidis]

My vote would be compulsory moving forward only, unless there are other ways to do version detection?

[chris-little]

I am happy for Mandatory for future versions, e.g. V1.1. And absence implies V1.0. @tomkralidis

@jonblower Do you think that this is not a completely backward compatible change? Isn't an unidentified JSON object or attribute or property ignored? If so, could we make this V1.0.1. I agree tagging is needed.