Compatibility with pandoc 1.16.0.1

[pikapikapo]

Hello,

It seems that the current version is not compatible with the latests pandoc versions.

Doing this minor tweak fixed it for me (from jgm/pandoc-types@545a57e) :

--- a/src/Text/Pandoc/R.hs
+++ b/src/Text/Pandoc/R.hs
@@ -54,7 +54,7 @@ readImgFiles attrs = case lookup "files" attrs of
    Nothing -> [defFile]

 insertImage :: FilePath -> Inline
-insertImage file = Image [] (file,"")
+insertImage file = Image nullAttr [] (file, "")

 --plot the R graph
 --the files created will be the one specified in the R code with commands such as:

Regards,
Jérôme