Distinguish between dependent and independent styles when validating

[rmzelle]

The CSL schema should probably be more strict for dependent styles (e.g. it shouldn't allow for stuff like style-options (punctuation-in-quote) on cs:style).

[bdarcus]

So that would probably suggest something like:

start = base | dependent
dependent = element cs:style { info }

[rmzelle]

See 36b2d4d

[rmzelle]

And 957a32f

[rmzelle]

See also

0a47df6
56cc0c9
874daed

[rmzelle]

With this ticket, I split up the schema to have different requirements for dependent and independent styles, and I disallowed a few attributes and attribute values for each. A while back, I cleaned up the style repository so that all styles would upgrade correctly to CSL 1.0.1 and still be valid.

However, I've become worried that older CSL 1.0 styles in the wild (e.g. those installed by Zotero users) might become invalid CSL 1.0.1 styles, so I've relaxed the validation requirements again: ac98d78

The affected attributes/values are labelled in the schema as "legacy" or "obsolete". They can be removed in the CSL 1.1 schema, and stripped from the styles through the CSL 1.1 style upgrade XSLT.

[rmzelle]

For removing obsolete attributes/values, see #58.