PowerPoint writer: Treat lists inside BlockQuotes as lists

We don't yet produce incremental lists in PowerPoint, but we should at
least treat lists inside BlockQuotes as lists, for compatibility with
other slide formats.

src/Text/Pandoc/Writers/Powerpoint.hs

@@ -369,6 +369,12 @@ inlineToParElems (Span _ ils) = concatMapM inlineToParElems ils
 inlineToParElems (RawInline _ _) = return []
 inlineToParElems _ = return []
 
+isListType :: Block -> Bool
+isListType (OrderedList _ _) = True
+isListType (BulletList _) = True
+isListType (DefinitionList _) = True
+isListType _ = False
+
 blockToParagraphs :: PandocMonad m => Block -> P m [Paragraph]
 blockToParagraphs (Plain ils) = do
   parElems <- inlinesToParElems ils
@@ -386,7 +392,13 @@ blockToParagraphs (LineBlock ilsList) = do
 blockToParagraphs (CodeBlock attr str) =
   local (\r -> r{envParaProps = def{pPropMarginLeft = Just 100}}) $
   blockToParagraphs $ Para [Code attr str]
--- TODO: work out the format
+-- We can't yet do incremental lists, but we should render a
+-- (BlockQuote List) as a list to maintain compatibility with other
+-- formats.
+blockToParagraphs (BlockQuote (blk : blks)) | isListType blk = do
+  ps  <- blockToParagraphs blk
+  ps' <- blockToParagraphs $ BlockQuote blks
+  return $ ps ++ ps'
 blockToParagraphs (BlockQuote blks) =
   local (\r -> r{ envParaProps = (envParaProps r){pPropMarginLeft = Just 100}
                 , envRunProps = (envRunProps r){rPropForceSize = Just blockQuoteSize}})$