Sanitize descriptions in code generator

[wwerner]

Currently, both the editor and the display support markdown formatting.
As (I think) the description will be rendered into the generated code's comments, we need to make sure that this does not break the target syntax.

This is also true for arbitrary comments.

[VaughnVernon]

@wwerner Do you mean using AJAX to compile check on perhaps line-by-line changes?

[wwerner]

No, I thought we'd check validity/escape/sanitize content on the server side when the user saves content, as the request can come from our UI as well as from some other API client.

We could additionally hook into Monaco Editor's highlighting to show invalid content.

Just for traceability: Referring to #35 (comment), I was under the impression that the Description in SchemaVersion would be part of the sources generated from the Specification, probably in the comments.

[VaughnVernon]

@wwerner Ah, ok, good point. Let's do generate comments for the (sanitized) description.