rework post processor callbacks

gallery_dl/postprocessor/common.py

@@ -16,25 +16,5 @@ class PostProcessor():
         name = self.__class__.__name__[:-2].lower()
         self.log = job.get_logger("postprocessor." + name)
 
-    @staticmethod
-    def prepare(pathfmt):
-        """Update file paths, etc."""
-
-    @staticmethod
-    def run(pathfmt):
-        """Execute the postprocessor for a file"""
-
-    @staticmethod
-    def run_metadata(pathfmt):
-        """Execute the postprocessor for a file"""
-
-    @staticmethod
-    def run_after(pathfmt):
-        """Execute postprocessor after moving a file to its target location"""
-
-    @staticmethod
-    def run_final(pathfmt, status):
-        """Postprocessor finalization after all files have been downloaded"""
-
     def __repr__(self):
         return self.__class__.__name__