Complete default values for check-boxes in LaTeX exporter

* lisp/org-latex.el (org-export-latex-list-parameters): complete
  default value with cbtrans option.
* lisp/org-list.el (org-list-to-latex): set a more consistent default
  value.

lisp/org-latex.el

@@ -391,7 +391,7 @@ string should be like \"\\end{itemize\"."
 		 (string :tag "Use a section string" :value "\\subparagraph{%s}")))
 
 (defcustom org-export-latex-list-parameters
-  '(:cbon "$\\boxtimes$" :cboff "$\\Box$")
+  '(:cbon "$\\boxtimes$" :cboff "$\\Box$" :cbtrans "$\\boxminus$")
   "Parameters for the LaTeX list exporter.
 These parameters will be passed on to `org-list-to-latex', which in turn
 will pass them (combined with the LaTeX default list parameters) to

lisp/org-list.el

@@ -3109,7 +3109,7 @@ with overruling parameters for `org-list-to-generic'."
 			   "\\item "))
 	       :csep "\n"
 	       :cbon "\\texttt{[X]}" :cboff "\\texttt{[ ]}"
-	       :cbtrans "$\\boxminus$")
+	       :cbtrans "\\texttt{[-]}")
     params)))
 
 (defun org-list-to-html (list &optional params)