Core as subtree

[duckontheweb]

Related Issue(s):
#114

Proposed Changes:

1. Make stac-spec a git subtree instead of a git submodule

PR Checklist:

• This PR is made against the dev branch (all proposed changes except releases should be against dev, not master).
• This PR has no breaking changes.
• I have added my changes to the CHANGELOG or a CHANGELOG entry is not required.

[duckontheweb]

@cholmes @matthewhanson @m-mohr This a demo of what it would look like have stac-spec embedded as a subtree instead of a submodule. A couple of things to note:

• This is currently using v1.0.0-rc.2 of stac-spec. When we want to update, we will need to use git subtree pull from the new core spec version.
• Links to core spec docs (e.g. Catalog, Collection) will be to files in this repo and not in radiantearth/stac-spec.
• I added an item to the PR checklist to help contributors remember not to change anything in the stac-spec directory. If a subtree seems like the right way to go, I'll look into adding a CI check as well.

[duckontheweb]

Also, looks like the failing tests are due to invalid links to the stac-spec/extensions folder that no longer exists now that extensions have been moved.

[duckontheweb]

I'll fix the broken extension links and add a CI check so you all can review this properly.

[duckontheweb]

@cholmes @m-mohr @matthewhanson This is ready for review.

I added an npm command to check for changes to the stac-spec directory against the given revision/branch. It will return a -1 exit code if there have been changes. Also added this as a job in the CircleCI config.

[m-mohr]

This is meant to be used by CI only, right? As I think this would fail on any other system (at least on Win), maybe just use that command directly in the CI without exposing it as npm script?

[duckontheweb]

It can be run locally (I've been using it to test prior to putting in the PR to avoid unexpected CI failures). You just need to pass in the --compare-to option manually when running it locally:

npm run check-stac-spec-changes --compare-to=master

[duckontheweb]

I think this would fail on any other system (at least on Win)

You may be right about Windows, I've only tested on Linux and MacOS.

[m-mohr]

Not ideal, but probably the best solution that we can get right now. Thanks for doing it. Left one comment, otherwise lgtm.

[duckontheweb]

Not ideal, but probably the best solution that we can get right now. Thanks for doing it. Left one comment, otherwise lgtm.

Yeah, I totally agree, this feel really heavy-handed for such a simple problem. If a better solution comes along we should definitely take advantage.