Support inlining year numbers / "draft"

[bakkot]

The annual published versions of ECMA-262 want to refer to that year's ECMA-402, and conversely. But we are definitely not going to remember to make that change manually, as evidenced by the fact that we have forgotten to do this on seven consecutive years.

Ecmarkup should have support in some form for a marker to be replaced by a defined year number, instead of us manually updating it every time. And for drafts, we might want to insert "Draft" in places.