Reverted "omit blank lines after list items," better fix for #1777.

Now we do as before, including blank lines after list items in
loose lists (even though RST doesn't care -- this is just a matter
of visual appeal).  But we chomp any excess whitespace after the
last list item, which solves #1777.

src/Text/Pandoc/Writers/RST.hs

@@ -252,7 +252,7 @@ blockToRST (Table caption _ widths headers rows) =  do
 blockToRST (BulletList items) = do
   contents <- mapM bulletListItemToRST items
   -- ensure that sublists have preceding blank line
-  return $ blankline $$ vcat contents $$ blankline
+  return $ blankline $$ chomp (vcat contents) $$ blankline
 blockToRST (OrderedList (start, style', delim) items) = do
   let markers = if start == 1 && style' == DefaultStyle && delim == DefaultDelim
                    then take (length items) $ repeat "#."
@@ -264,17 +264,17 @@ blockToRST (OrderedList (start, style', delim) items) = do
   contents <- mapM (\(item, num) -> orderedListItemToRST item num) $
               zip markers' items
   -- ensure that sublists have preceding blank line
-  return $ blankline $$ vcat contents $$ blankline
+  return $ blankline $$ chomp (vcat contents) $$ blankline
 blockToRST (DefinitionList items) = do
   contents <- mapM definitionListItemToRST items
   -- ensure that sublists have preceding blank line
-  return $ blankline $$ vcat contents $$ blankline
+  return $ blankline $$ chomp (vcat contents) $$ blankline
 
 -- | Convert bullet list item (list of blocks) to RST.
 bulletListItemToRST :: [Block] -> State WriterState Doc
 bulletListItemToRST items = do
   contents <- blockListToRST items
-  return $ hang 3 "-  " contents
+  return $ hang 3 "-  " $ contents <> cr
 
 -- | Convert ordered list item (a list of blocks) to RST.
 orderedListItemToRST :: String   -- ^ marker for list item
@@ -283,7 +283,7 @@ orderedListItemToRST :: String   -- ^ marker for list item
 orderedListItemToRST marker items = do
   contents <- blockListToRST items
   let marker' = marker ++ " "
-  return $ hang (length marker') (text marker') contents
+  return $ hang (length marker') (text marker') $ contents <> cr
 
 -- | Convert defintion list item (label, list of blocks) to RST.
 definitionListItemToRST :: ([Inline], [[Block]]) -> State WriterState Doc
@@ -291,7 +291,7 @@ definitionListItemToRST (label, defs) = do
   label' <- inlineListToRST label
   contents <- liftM vcat $ mapM blockListToRST defs
   tabstop <- get >>= (return . writerTabStop . stOptions)
-  return $ label' $$ nest tabstop (nestle contents)
+  return $ label' $$ nest tabstop (nestle contents <> cr)
 
 -- | Convert list of Pandoc block elements to RST.
 blockListToRST :: [Block]       -- ^ List of block elements

tests/writer.rst

@@ -136,7 +136,9 @@ Asterisks tight:
 Asterisks loose:
 
 -  asterisk 1
+
 -  asterisk 2
+
 -  asterisk 3
 
 Pluses tight:
@@ -148,7 +150,9 @@ Pluses tight:
 Pluses loose:
 
 -  Plus 1
+
 -  Plus 2
+
 -  Plus 3
 
 Minuses tight:
@@ -160,7 +164,9 @@ Minuses tight:
 Minuses loose:
 
 -  Minus 1
+
 -  Minus 2
+
 -  Minus 3
 
 Ordered
@@ -181,13 +187,17 @@ and:
 Loose using tabs:
 
 1. First
+
 2. Second
+
 3. Third
 
 and using spaces:
 
 1. One
+
 2. Two
+
 3. Three
 
 Multiple paragraphs:
@@ -195,7 +205,9 @@ Multiple paragraphs:
 1. Item 1, graf one.
 
    Item 1. graf two. The quick brown fox jumped over the lazy dog’s back.
+
 2. Item 2.
+
 3. Item 3.
 
 Nested
@@ -215,25 +227,30 @@ Here’s another:
    -  Fee
    -  Fie
    -  Foe
+
 3. Third
 
 Same thing but with paragraphs:
 
 1. First
+
 2. Second:
 
    -  Fee
    -  Fie
    -  Foe
+
 3. Third
 
 Tabs and spaces
 ---------------
 
 -  this is a list item indented with tabs
+
 -  this is a list item indented with spaces
 
    -  this is an example list item indented with tabs
+
    -  this is an example list item indented with spaces
 
 Fancy list markers
@@ -300,8 +317,10 @@ Loose:
 
 apple
     red fruit
+
 orange
     orange fruit
+
 banana
     yellow fruit
 
@@ -311,6 +330,7 @@ Multiple blocks with italics:
     red fruit
 
     contains seeds, crisp, pleasant to taste
+
 *orange*
     orange fruit
 
@@ -335,6 +355,7 @@ apple
     red fruit
 
     computer
+
 orange
     orange fruit
 
@@ -346,6 +367,7 @@ apple
     red fruit
 
     computer
+
 orange
     orange fruit
 
@@ -644,6 +666,7 @@ LaTeX
 -  Here’s some display math:
 
    .. math:: \frac{d}{dx}f(x)=\lim_{h\to 0}\frac{f(x+h)-f(x)}{h}
+
 -  Here’s one that has a line break in it: :math:`\alpha + \omega \times x^2`.
 
 These shouldn’t be math: