Use char-after instead of buffer-substring in toggle-keyword-string

Replace verbose buffer-substring-no-properties single-char comparisons
with direct char-after calls, and use = instead of equal for the
numeric point comparison.

Author: bbatsov

clojure-mode.el

@@ -2005,15 +2005,15 @@ nil."
   (interactive)
   (let ((original-point (point)))
     (while (and (> (point) 1)
-                (not (equal "\"" (buffer-substring-no-properties (point) (+ 1 (point)))))
-                (not (equal ":" (buffer-substring-no-properties (point) (+ 1 (point))))))
+                (not (eq ?\" (char-after)))
+                (not (eq ?: (char-after))))
       (backward-char))
     (cond
-     ((equal 1 (point))
+     ((= 1 (point))
       (error "Beginning of file reached, this was probably a mistake"))
-     ((equal "\"" (buffer-substring-no-properties (point) (+ 1 (point))))
+     ((eq ?\" (char-after))
       (insert ":" (substring (clojure-delete-and-extract-sexp) 1 -1)))
-     ((equal ":" (buffer-substring-no-properties (point) (+ 1 (point))))
+     ((eq ?: (char-after))
       (insert "\"" (substring (clojure-delete-and-extract-sexp) 1) "\"")))
     (goto-char original-point)))