Clean-up spec and JSON Schema

[m-mohr]

Fixes #129, should include not functional changes.

Changes:

1. Updated the datatype for the columns key from key to string in the written spec as "key" is not a datatype
2. Added the missing null type to the crs field in the written spec (alignment with JSON Schema)
3. Minor text and/or formatting changes without functional changes.
4. Removed all descriptions from the JSON Schema. It seems they were not updated everytimg when changes were applied to the spec. To mitigate the risk of differences between the written spec and the schema, I'd recommend to not duplicate descriptions in the schema. They are annotations only anyway and are not used for validation.
5. Moved required fields up so that they are located before the properties, which makes it easier to understand the requirements
6. Keep annotation-style fields together for easier understanding.
7. Replaced patternProperties pattern ".*" with ".+" to not allow empty column names (see Require minimum length of 1 for primary_geometry #129 #153)
8. Removed all additionalProperties: true as they are the default anyway
9. Replaced enums with a single value with const
10. Don't allow additional columns that are invalid

Related PRs: #151, #153

[kylebarron]

A lot of good changes (the STAC experience shows!) though I think it would be easier to review/discuss if split into a few different PRs.

[m-mohr]

@kylebaron The issue is the indentation change for patternProperties/additionalProperties. Makes it a bit hard to compare in the underwhelming GitHub diff tool. Maybe open it in a another diff tool?

[kylebarron]

@kylebaron The issue is the indentation change for patternProperties/additionalProperties.

I was referring more towards:

• Whether to declare Z in the geom type; whether to use a regex there
• Whether crs should allow null
• Exactly how bbox should be defined in the schema

I think it would be clearer for each to be their own PR with their own discussion

[m-mohr]

I'll rebase this after #88 and #140 have been merged.

[m-mohr]

Updated to reflect the latest changes. See the initial post for a list of changes.

[m-mohr]

Two additional changes, see also #141 (comment):

1. Replaced patternProperties pattern ".*" with ".+" to not allow empty column names (see Require minimum length of 1 for primary_geometry #129 #153)
2. Don't allow additional columns that are invalid

[m-mohr]

Wasn't this meant to wait for #141 ?

[tschaub]

My bad. I thought I understood that this was going to come first. I had just read the comment here #141 (comment) and thought that the tests were going to be adapted after this was in.

@jorisvandenbossche - Apologies for complicating things if the tests don't pass with these changes.

[jorisvandenbossche]

No problem! The tests are also still passing, so no complication at all ;)