defined boolean attribute type

[davidcarlisle]

Add a boolean attrbute type (refencing the existing definition in MathML-Core), replace all "true" | "false" by a reference to boolean.

This addresses a main case highlighted by #178

[NSoiffer]

Nothing wrong with this as a start, but don't most of the attribute values need to be ASCII case insensitive? Or do you think only those that use boolean values?

[davidcarlisle]

@NSoiffer I think values that are case insensitive in mathml-core need to be case insensitive in full, so that anything valid in core is valid in full (and that's already what the schema implemented even though the spec wording did not). Making other things case insensitive is possibly the right thing to do but less important I think. Certainly in an xml world there is less pressure to be case insensitive, eg xml schema for xhtml and svg are typically case sensitive, it is the versions embedded in html where this is most natural.

But I was not suggesting that we don't change the others, just doing a simple but important case as low hanging fruit, that could easily be done and reviewed on a wet afternoon.

[NSoiffer]

Yes, very sensible. I'll open an issue on whether we should make all the fixed value ones (such as "left"/"center"/"right") be case sensitive or not. If we decide not to, then there's nothing to do.