ox-latex: Allow to span documentclass options accross multiple lines in template

* contrib/lisp/ox-koma-letter.el (org-koma-letter-template): Allow to
  span documentclass options accross multiple lines in template.
* lisp/ox-beamer.el (org-beamer-template): Allow to span documentclass
  options accross multiple lines in template.
* lisp/ox-latex.el (org-latex-template): Allow to span documentclass
  options accross multiple lines in template.

Thanks to Michael Strey for reporting this bug.

contrib/lisp/ox-koma-letter.el

@@ -183,11 +183,10 @@ holding export options."
       (let* ((header (nth 1 (assoc class org-latex-classes)))
              (document-class-string
               (and (stringp header)
-                   (if class-options
-                       (replace-regexp-in-string
-                        "^[ \t]*\\\\documentclass\\(\\[.*?\\]\\)"
-                        class-options header t nil 1)
-                     header))))
+                   (if (not class-options) header
+		     (replace-regexp-in-string
+		      "^[ \t]*\\\\documentclass\\(\\(\\[[^]]*\\]\\)?\\)"
+		      class-options header t nil 1)))))
         (if (not document-class-string)
 	    (user-error "Unknown LaTeX class `%s'")
           (org-latex-guess-babel-language

lisp/ox-beamer.el

@@ -841,7 +841,7 @@ holding export options."
 		(and (stringp header)
 		     (if (not class-options) header
 		       (replace-regexp-in-string
-			"^[ \t]*\\\\documentclass\\(\\(\\[.*\\]\\)?\\)"
+			"^[ \t]*\\\\documentclass\\(\\(\\[[^]]*\\]\\)?\\)"
 			class-options header t nil 1)))))
 	  (if (not document-class-string)
 	      (user-error "Unknown LaTeX class `%s'" class)

lisp/ox-latex.el

@@ -1109,7 +1109,7 @@ holding export options."
 		(and (stringp header)
 		     (if (not class-options) header
 		       (replace-regexp-in-string
-			"^[ \t]*\\\\documentclass\\(\\(\\[.*\\]\\)?\\)"
+			"^[ \t]*\\\\documentclass\\(\\(\\[[^]]*\\]\\)?\\)"
 			class-options header t nil 1)))))
 	  (if (not document-class-string)
 	      (user-error "Unknown LaTeX class `%s'" class)