rename fullnames

Handle a couple places with `t3_` that persisted from code movement.
on master after time of branch.

Then, fix commenting, which used inaccurate fullname parsing logic.

files/classes/submission.py

@@ -164,7 +164,7 @@ class Submission(CreatedBase):
 	@property
 	@lazy
 	def fullname(self):
-		return f"t2_{self.id}"	
+		return f"post_{self.id}"	
 
 	@property
 	@lazy