Add tag extractor

app/EpubParser.hs

@@ -47,6 +47,12 @@ getOpfPath archive = do
     (t:_) -> Just (fromAttrib "full-path" t)
     []    -> Nothing
   
+getOpfTags :: Archive -> FilePath -> [Tag String]
+getOpfTags archive opfpath =
+  case findEntryByPath opfpath archive of
+    Just entry -> parseTags $ C8.unpack (fromEntry entry)
+    Nothing    -> []
+
 getRootPrefix :: FilePath -> FilePath
 getRootPrefix path = 
     let dir = takeDirectory path