Speed up the events view.

We do this with the help of some denormalisation
and a handy trigger.

Closes #35.

bin/system_imports.py

@@ -48,5 +48,8 @@ if __name__ == '__main__':
 			db.conn.commit()
 			# Update the sequences that generate event ids
 			cur.execute("SELECT reset_events_serials();")
+			# Let us ensure events_timed_seq is up to date, even though
+			# the triggers will have taken care of this already.
+			cur.execute("CALL events_timed_seq_update_all();")
 
 	print("Done")