Use splitDirectories istead of splitPath.

We were using `splitPath` in two places in the code
where `splitDirectories` should have been used.

This led to a test for `..` in paths in `extractMedia`
failing, so that images with `..` in the path name
could be extracted outside the directory specified
by `extractMedia`.

It also led a test for `media` in resource paths to fail
in the docx reader.

src/Text/Pandoc/MediaBag.hs

@@ -80,7 +80,7 @@ insertMedia fp mbMime contents (MediaBag mediamap) =
         uri = parseURI fp
         newpath = if isRelative fp
                        && isNothing uri
-                       && ".." `notElem` splitPath fp
+                       && ".." `notElem` splitDirectories fp
                      then T.unpack fp'
                      else showDigest (sha1 contents) <> "." <> ext
         fallback = case takeExtension fp of

src/Text/Pandoc/Readers/Docx/Parse.hs

@@ -505,7 +505,7 @@ archiveToRelationships archive docXmlPath =
 
 filePathIsMedia :: FilePath -> Bool
 filePathIsMedia fp =
-  "media" `elem` splitPath (takeDirectory fp)
+  "media" `elem` splitDirectories (takeDirectory fp)
 
 lookupLevel :: T.Text -> T.Text -> Numbering -> Maybe Level
 lookupLevel numId ilvl (Numbering _ numbs absNumbs) = do