* lisp/calc/: Use lexical scoping in all the files

Includes the following pervasive changes:
- Move some defvars earlier in the file so they cover earlier let-bindings
- Change dynamically scoped `calc-FOO` or `math-FOO` function arguments
  to just FOO and then let-bind the `calc-FOO` or `math-FOO` variable
  explicitly in the body of the function.  In some cases, the
  beginning of the function was changed to refer to FOO so as to delay
  the binding to a nearby `let` when I could ensure that it did
  not make a difference.
- Add an underscore in front of unused vars or comment them out altogether.
- Replace unused `err` arg to `condition-case` with nil.

Plus the additional itemized changes below.

* lisp/calc/calc-map.el (calcFunc-reducer):
* lisp/calc/calc-arith.el (math-setup-declarations):
* lisp/calc/calc-help.el (calc-full-help, calc-help-index-entries)
(calc-full-help): Use `ignore-errors`.

* lisp/calc/calc-embed.el (calc-embedded-modes-change):
Declare `the-language` and `the-display-just` as dynamically scoped.

* lisp/calc/calc-forms.el (math-setup-year-holidays): Use `dolist`.

* lisp/calc/calc-graph.el (calc-graph-set-styles): Use `symbol-value`
rather than `eval.`
(calc-graph-delete-temps, calc-graph-set-styles): Use ignore-errors.

* lisp/calc/calc-macs.el (calc-with-trail-buffer): Add artificial use
of `save-buf` to silence compiler warnings in all the cases where
`body` doesn't make use of it.

* lisp/calc/calc-math.el (math-largest-emacs-expt)
(math-smallest-emacs-expt, math-use-emacs-fn): Use ignore-errors.

* lisp/calc/calc-mode.el (calc-total-algebraic-mode): Remove "P" from
interactive spec since it's not used anyway.

* lisp/calc/calc-rewr.el (calc-match): Simplify.

* lisp/calc/calc.el (calc-buffer): Give it a global nil value,
so it's automatically declared dynbound in any file that requires `calc`.
(calcDigit-nondigit): Adjust accordingly.

* lisp/calc/calcalg2.el (calcFunc-table): Declare `var-dummy` as dynbound.
(math-scan-for-limits): Comment out dead code.

* lisp/calc/calcalg3.el (math-general-fit): Declare `var-YVAL` and
`var-YVALX` as dynbound.

1 files changed, 2 insertions, 2 deletions

diff --git a/lisp/calc/calc.el b/lisp/calc/calc.el
index bf8b006d7c6..bde7bd4e2bd 100644
--- a/lisp/calc/calc.el
+++ b/lisp/calc/calc.el
@@ -2313,7 +2313,7 @@ the United States."
         ((eq last-command-event ?@) "0@ ")
         (t (char-to-string last-command-event))))
 
-(defvar calc-buffer)
+(defvar calc-buffer nil)
 (defvar calc-prev-char)
 (defvar calc-prev-prev-char)
 (defvar calc-digit-value)
@@ -2353,7 +2353,7 @@ the United States."
 (defun calcDigit-nondigit ()
   (interactive)
   ;; Exercise for the reader:  Figure out why this is a good precaution!
-  (or (boundp 'calc-buffer)
+  (or calc-buffer
       (use-local-map minibuffer-local-map))
   (let ((str (minibuffer-contents)))
     (setq calc-digit-value (with-current-buffer calc-buffer