accessibility annotations for presentation MathML 4

[dginev]

Since the last call of the "Accessibility for MathML" has started discussing prototype ideas, we should try to offer a demo capability in a standalone branch of latexml? And at least discuss implementation paths.

My thoughts on what I'd like to try:

• a math post-processor that acts as an alternative to the Content MathML processor, running after/in parallel to the Presentation post-processor and adding the attributes. Maybe the easiest first stab is to run both pmml and cmml and walk through the xrefs adding attributes...
• once we have these generated, I'm thinking of writing a small javascript application that uses the attributes to serialize out a full English word verbalization of each formula.
• iterate over enough examples to feel it's reasonable... ?