EPUB writer: stylesheet changes. Closes #2040.

* Allow `--css` to be used to specify stylesheets.
* Deprecated `--epub-stylesheet` and made it a synoynym of
  `--css`.
* If a code block with class "css" is given as contents of the
  `stylesheet` metadata field, use its literal code as contents of
  the epub stylesheet.  Otherwise, treat it as a filename and
  read the file.
* Note: `--css` and `stylesheet` in metadata are not compatible.
  `stylesheet` takes precedence.

1 files changed, 4 insertions, 2 deletions

diff --git a/pandoc.hs b/pandoc.hs
index 9023b2625..45e5de5f2 100644
--- a/pandoc.hs
+++ b/pandoc.hs
@@ -689,8 +689,10 @@ options =
     , Option "" ["epub-stylesheet"]
                  (ReqArg
                   (\arg opt -> do
-                     text <- UTF8.readFile arg
-                     return opt { optEpubStylesheet = Just text })
+                     warn "--epub-stylesheet is deprecated. Use --css or stylesheet in metadata."
+                     let newvars = optVariables opt ++ [("css",arg)]
+                     return opt { optVariables = newvars,
+                                  optStandalone = True })
                   "FILENAME")
                  "" -- "Path of epub.css"