Switch from pretty-simple to pretty-show for native output.

Update tests.

Reason:  it turns out that the native output generated by
pretty-simple isn't always readable by the native reader.
According to https://github.com/cdepillabout/pretty-simple/issues/99
it is not a design goal of the library that the rendered values
be readable using 'read'.  This makes it unsuitable for our
purposes.

pretty-show is a bit slower and it uses 4-space indents
(non-configurable), but it doesn't have this serious drawback.

1 files changed, 29 insertions, 28 deletions

diff --git a/test/command/934.md b/test/command/934.md
index 195d5602e..3c86a1f26 100644
--- a/test/command/934.md
+++ b/test/command/934.md
@@ -8,36 +8,37 @@
 \ddb{This should be italic and in quotes}{And this is the attribution}
 ^D
 [ Para
-  [ Emph
-    [ Quoted DoubleQuote
-      [ Str "This"
-      , Space
-      , Str "should"
-      , Space
-      , Str "be"
-      , Space
-      , Str "italic"
-      , Space
-      , Str "and"
-      , Space
-      , Str "in"
-      , Space
-      , Str "quotes"
-      ]
+    [ Emph
+        [ Quoted
+            DoubleQuote
+            [ Str "This"
+            , Space
+            , Str "should"
+            , Space
+            , Str "be"
+            , Space
+            , Str "italic"
+            , Space
+            , Str "and"
+            , Space
+            , Str "in"
+            , Space
+            , Str "quotes"
+            ]
+        ]
     ]
-  ]
 , Para
-  [ Strong
-    [ Str "And"
-    , Space
-    , Str "this"
-    , Space
-    , Str "is"
-    , Space
-    , Str "the"
-    , Space
-    , Str "attribution"
+    [ Strong
+        [ Str "And"
+        , Space
+        , Str "this"
+        , Space
+        , Str "is"
+        , Space
+        , Str "the"
+        , Space
+        , Str "attribution"
+        ]
     ]
-  ]
 ]
 ```