fix `read-syntax' on a vector with a size and no given elements

Closes PR 13720
scribble/manual: make `defmodule' more flexible
use new `defmodule' in the Reference notation section
add c:x;m keyboard shortcut for renaming bound variables
adjust check syntax keyboard shortcuts

- make them use the same names as the context menu items
- add c:x;a to tack/untack arrows
Fix Guide typo

Closes PR 13695
add stub for enumeration support to Redex
fixing error message in rewrite-side-conditions.rkt
specified match precedence in lexer... hope I'm right