delete answer when question is deleted

knowledge_base/doctype/question/question.py

@@ -0,0 +1,8 @@
+class DocType:
+	def __init__(self, d, dl):
+		self.doc, self.doclist = d, dl
+		
+	def on_trash(self):
+		import webnotes
+		webnotes.conn.sql("delete from tabAnswer where question=%s", self.doc.name)
+