Add ability to remove caption from PDF output

See LaurentRDC#37.

For whatever reason, the change introduced in the PR related to the
issue above seems to not have an effect any more. Bring that change
back. Seems we might have problems with pandoc-crossref and other
filters because of which the change was dropped but right now this
is the only filter we care about.

src/Text/Pandoc/Filter/Plot/Embed.hs

@@ -31,9 +31,9 @@ import Text.HTML.TagSoup
   )
 import Text.Pandoc.Builder as Builder
   ( Inlines,
-    figureWith,
     fromList,
     imageWith,
+    para,
     link,
     plain,
     simpleCaption,
@@ -88,16 +88,10 @@ figure ::
   Inlines ->
   PlotM Block
 figure as fp caption' =
-  return . head . toList $
-    if null caption'
-      -- If there is no caption, a LaTeX figure may look strange. See #37
-      then plain $ imageWith as (pack fp) mempty caption'
-      else 
-        -- We want the attributes both on the Figure element and the contained Image element
-        -- so that pandoc-plot plays nice with pandoc-crossref and other filters
-        figureWith as (simpleCaption (plain caption')) $
-          plain $
-            imageWith as (pack fp) mempty caption'
+  return . head . toList . para $
+    imageWith as (pack fp) title caption'
+  where
+    title = if caption' /= mempty then "fig:" else mempty
 
 -- TODO: also add the case where SVG plots can be
 --       embedded in HTML output
@@ -188,11 +182,11 @@ extractPlot :: Text -> Text
 extractPlot t =
   let tags = canonicalizeTags $ parseTagsOptions parseOptionsFast t
       extracted = headScripts tags <> [inside "body" tags]
-   in -- In the past (e.g. commit 8417b011ccb20263427822c7447840ab4a30a41e), we used to
+      -- In the past (e.g. commit 8417b011ccb20263427822c7447840ab4a30a41e), we used to
       -- make all JS scripts 'deferred'. This turned out to be problematic for plotly
       -- specifically (see issue #39). In the future, we may want to defer scripts for
       -- certain toolkits, but that's a testing nightmare...
-      mconcat $ renderTags <$> extracted
+   in mconcat $ renderTags <$> extracted
   where
     headScripts = partitions (~== ("<script>" :: String)) . inside "head"