org-e-latex: Display nicer horizontal rules

* contrib/lisp/org-e-latex.el (org-e-latex-horizontal-rule): Display
  nicer horizontal rules. Support :width and :thickness attributes.

contrib/lisp/org-e-latex.el

@@ -1453,10 +1453,20 @@ holding contextual information."
 (defun org-e-latex-horizontal-rule (horizontal-rule contents info)
   "Transcode an HORIZONTAL-RULE  object from Org to LaTeX.
 CONTENTS is nil.  INFO is a plist holding contextual information."
-  (let ((attr (mapconcat #'identity
-			 (org-element-property :attr_latex horizontal-rule)
-			 " ")))
-    (org-e-latex--wrap-label horizontal-rule (concat "\\hrule " attr))))
+  (let ((attr (org-export-read-attribute :attr_latex horizontal-rule))
+	(prev (org-export-get-previous-element horizontal-rule info)))
+    (concat
+     ;; Make sure the rule doesn't start at the end of the current
+     ;; line by separating it with a blank line from previous element.
+     (when (and prev
+		(let ((prev-blank (org-element-property :post-blank prev)))
+		  (or (not prev-blank) (zerop prev-blank))))
+       "\n")
+     (org-e-latex--wrap-label
+      horizontal-rule
+      (format "\\rule{%s}{%s}"
+	      (or (plist-get attr :width) "\\linewidth")
+	      (or (plist-get attr :thickness) "0.5pt"))))))
 
 
 ;;;; Inline Babel Call