Powerpoint writer: consolidate text run nodes.

This should reduce the size of the generated files.

src/Text/Pandoc/Writers/Powerpoint/Presentation.hs

@@ -348,7 +348,15 @@ instance Default PicProps where
 --------------------------------------------------
 
 inlinesToParElems :: [Inline] -> Pres [ParaElem]
-inlinesToParElems ils = concatMapM inlineToParElems ils
+inlinesToParElems = concatMapM inlineToParElems . consolidateStrs
+ where
+  -- we combine Str + Space combinations, because this makes
+  -- the resulting ooxml much more compact, with fewer independent
+  -- text run elements
+  consolidateStrs [] = []
+  consolidateStrs (Str t : Space : ils) = consolidateStrs (Str (t <> " ") : ils)
+  consolidateStrs (Space : Str t : ils) = consolidateStrs (Str (" " <> t) : ils)
+  consolidateStrs (il : ils) = il : consolidateStrs ils
 
 inlineToParElems :: Inline -> Pres [ParaElem]
 inlineToParElems (Str s) = do