…verbs after the "nor" and add punctuation.

module/import/export as macros before encountering a module/import
directive.

the updated grammar.

first token in the sequence [...]".

Avoids a grammar description immediately following an example.

resolves a parse ambiguity rather than determining program validity.

Move export-keyword, import-keyword, and module-keyword out of our table
of keyword identifiers (where they don't fit) and make them directly be
grammar productions for keyword instead.