Suggested by Arash Esbati <arash@gnu.org>.

Also add a few missing docstrings.

* lisp/emacs-lisp/elisp-scope.el (elisp-scope-symbol-role-p)
(elisp-scope-read-symbol-role, elisp-scope-special-variables)
(elisp-scope-let, elisp-scope-let*): Add docstring.
(elisp-scope-counter, elisp-scope-callback)
(elisp-scope-current-let-alist-form, elisp-scope-local-new)
(elisp-scope-sym-pos, elisp-scope-sym-bare)
(elisp-scope-report, elisp-scope-special-variable-p)
(elisp-scope-let-1, elisp-scope-variable)
(elisp-scope-binding, elisp-scope-symbol): Rename, replace
'elisp-scope-' prefix with 'elisp-scope--' to indicate that
these are private.  Update all references.

* lisp/progmodes/elisp-mode.el (elisp)
(elisp-fontify-semantically, elisp-symbol-at-mouse)
(elisp-free-variable, elisp-special-variable-declaration)
(elisp-condition, elisp-major-mode-name, elisp-face)
(elisp-symbol-role, elisp-symbol-role-definition)
(elisp-function, elisp-non-local-exit, elisp-unknown-call)
(elisp-macro, elisp-special-form, elisp-throw-tag)
(elisp-feature, elisp-rx, elisp-theme, elisp-binding-variable)
(elisp-bound-variable, elisp-shadowing-variable)
(elisp-shadowed-variable, elisp-variable-at-point)
(elisp-warning-type, elisp-function-property-declaration)
(elisp-thing, elisp-slot, elisp-widget-type, elisp-type)
(elisp-group, elisp-nnoo-backend, elisp-ampersand)
(elisp-constant, elisp-defun, elisp-defmacro, elisp-defvar)
(elisp-defface, elisp-icon, elisp-deficon, elisp-oclosure)
(elisp-defoclosure, elisp-coding, elisp-defcoding)
(elisp-charset, elisp-defcharset, elisp-completion-category)
(elisp-completion-category-definition, elisp-add-help-echo)
(elisp-fontify-symbol-precedence-function): Add :version tags.

* lisp/emacs-lisp/elisp-scope.el: Fix references to meta-syntactic
variables in the commentary.
(elisp-scope-describe-symbol-role, coding, defcoding, charset)
(defcharset): Doc fixes.
(elisp-scope-safe-macros): Add :version tag.  Doc fix.

* doc/emacs/display.texi (Semantic Font Lock): Fix punctuation and
wording, improve cross-references and indexing.

* lisp/emacs-lisp/elisp-scope.el (elisp-scope-quoted-group):
Delete it.
(define-minor-mode, define-derived-mode): Simplify analyzers.

Use argument specs to analyze complex widget types.

* lisp/emacs-lisp/elisp-scope.el (elisp-scope-widget-type)
(elisp-scope-widget-type-1)
(elisp-scope-widget-type-keyword-arguments)
(elisp-scope-widget-type-arguments)
(elisp-scope-widget-type-arguments-1): Delete, no longer used.
(custom-declare-variable, define-widget): Simplify analyzers.
(elisp-scope--match-spec-to-arg): Add new 'list', 'and', and
'plist-and-then' parametric specs, and add 'widget-type' as a
new recursive spec.

* test/lisp/progmodes/elisp-mode-resources/semantic-highlighting.el
Add test.

Rename a couple of faces to solidify the convention that the
face name 'elisp-foo' implies "references to foo", not "foo
definitions".  For definitions we use 'elisp-deffoo' if foo is
only one word, or 'elisp-bar-baz-definition' otherwise.

* lisp/progmodes/elisp-mode.el (elisp-function-reference):
Rename to 'elisp-function'.
(elisp-macro-call): Rename to 'elisp-macro'.
(elisp-non-local-exit):
(elisp-unknown-call):
(elisp-special-form):
* lisp/emacs-lisp/elisp-scope.el:
* test/lisp/progmodes/elisp-mode-resources/semantic-highlighting.el:
Update references to renamed faces.

* lisp/progmodes/elisp-mode.el (elisp-fontify-semantically):
Fix typo in doc string.
(elisp--annotate-symbol-with-help-echo): Accept plain string
as value of ':help' symbol role property.
* lisp/emacs-lisp/elisp-scope.el: Remove unused symbol role
properties from all defined symbol roles.  Use plain strings
for ':help' instead of wrapping them with 'cl-constantly'.
Cease 'require'ing 'cl-lib', no longer needed in runtime.
(elisp-scope-define-symbol-role): Update doc string.

* doc/emacs/display.texi (Semantic Font Lock): New node.
* doc/emacs/emacs.texi: Update menu.
* etc/NEWS: Update relevant entry.
* lisp/emacs-lisp/elisp-scope.el: Expand commentary.
* doc/misc/elisp-semantic-highlighting.org: Delete it.

* lisp/emacs-lisp/elisp-scope.el (elisp-scope-if-let): Fix
handling of a plain symbol as one the bindings in an
'if-let*' form, as in (if-let* (foo) 'bar).

* test/lisp/progmodes/elisp-mode-resources/semantic-highlighting.el:
Test it.