Parse until EOF instead of adding a manual check.

src/MdToHTML.hs

@@ -154,9 +154,7 @@ parseLine :: ReadP MdToken
 parseLine = do
   skipSpaces
   -- Fail if we have reached the end of the document.
-  remaining <- look
-  when (null remaining) pfail
-  parsed <- parseMany parseLineToken
+  parsed <- manyTill parseLineToken eof
   return (Line parsed)
 
 -- Parse a paragraph, which is a 'Line' (can span multiple actual lines), separated by double-newlines.