Markdown writer: use \ for newline instead of two spaces at eol.

(Unless --strict.)

src/Text/Pandoc/Writers/Markdown.hs

@@ -439,7 +439,10 @@ inlineToMarkdown _ (Math DisplayMath str) =
   return $ "$$" <> text str <> "$$"
 inlineToMarkdown _ (TeX str) = return $ text str
 inlineToMarkdown _ (HtmlInline str) = return $ text str 
-inlineToMarkdown _ (LineBreak) = return $ "  " <> cr
+inlineToMarkdown opts (LineBreak) = return $
+  if writerStrictMarkdown opts
+     then "  " <> cr
+     else "\\" <> cr
 inlineToMarkdown _ Space = return space
 inlineToMarkdown opts (Cite (c:cs) lst)
   | writerCiteMethod opts == Citeproc = inlineListToMarkdown opts lst

tests/writer.markdown

@@ -41,7 +41,7 @@ item.
 
 Here’s one with a bullet. \* criminey.
 
-There should be a hard line break  
+There should be a hard line break\
 here.
 
 * * * * *