Fix several backslash typos in Elisp strings

* lisp/calendar/todo-mode.el (todo-files, todo-rename-file)
(todo-find-filtered-items-file, todo-reset-nondiary-marker)
(todo-reset-done-string, todo-reset-comment-string)
(todo-reset-highlight-item):
* lisp/erc/erc-networks.el (erc-networks-alist):
* lisp/gnus/gnus-art.el (gnus-button-handle-library):
* lisp/gnus/gnus-group.el (gnus-read-ephemeral-gmane-group-url):
* lisp/gnus/nntp.el (nntp-via-shell-prompt)
(nntp-telnet-shell-prompt):
* lisp/gnus/spam-report.el (spam-report-gmane-regex):
* lisp/image-dired.el (image-dired-rotate-original):
(image-dired-get-exif-file-name):
* lisp/international/latin1-disp.el (latin1-display-ucs-per-lynx):
* lisp/mail/undigest.el (rmail-digest-parse-rfc1153strict):
* lisp/mh-e/mh-letter.el (mh-file-is-vcard-p):
* lisp/mh-e/mh-mime.el (mh-file-mime-type-substitutions):
* lisp/net/shr-color.el (shr-color->hexadecimal):
* lisp/org/org-bibtex.el (org-bibtex-fields):
* lisp/org/org-docview.el (org-docview-export):
* lisp/org/org-entities.el (org-entities):
* lisp/org/ox-icalendar.el (org-icalendar-cleanup-string):
* lisp/progmodes/cperl-mode.el (cperl-indent-exp):
* lisp/progmodes/ebnf2ps.el (ebnf-file-suffix-regexp)
(ebnf-style-database):
* lisp/progmodes/idlw-help.el (idlwave-do-context-help1):
* lisp/progmodes/ruby-mode.el (ruby-imenu-create-index-in-block):
* lisp/progmodes/sql.el (sql-product-alist):
* lisp/progmodes/verilog-mode.el (verilog-error-regexp-emacs-alist)
(verilog-error-font-lock-keywords)
(verilog-assignment-operator-re):
* lisp/progmodes/vhdl-mode.el (vhdl-compiler-alist):
* lisp/textmodes/reftex-parse.el (reftex-parse-from-file):
* lisp/vc/add-log.el (change-log-version-number-regexp-list):
Fix typo by replacing ‘\’ with ‘\\’ in a string literal.
For example, to get the regular expression ‘\.’ use the string
literal "\\.", not "\." (which is equivalent to ".").
* lisp/emulation/viper-util.el (viper-glob-unix-files):
Remove stray ‘\j’ from string.
* lisp/gnus/nntp.el (nntp-via-shell-prompt)
(nntp-telnet-shell-prompt):
Treat > like $ when matching a shell prompt.
* lisp/progmodes/make-mode.el (makefile-browse):
Properly quote a diagnostic.

lisp/gnus/auth-source.el

@@ -362,7 +362,7 @@ If the value is not a list, symmetric encryption will be used."
   "Read one of CHOICES by `read-char-choice', or `read-char'.
 `dropdown-list' support is disabled because it doesn't work reliably.
 Only one of CHOICES will be returned.  The PROMPT is augmented
-with \"[a/b/c] \" if CHOICES is '\(?a ?b ?c\)."
+with \"[a/b/c] \" if CHOICES is \(?a ?b ?c)."
   (when choices
     (let* ((prompt-choices
             (apply 'concat (loop for c in choices