Do not send delete connection messages when it's superfluous

Dynamo deletes connectors without receiving corresponding message from Flood during:
1) deleting a node (it causes to deleting all its connectors);
2) adding a connector into an input port (it causes to deleting existing connector);
3) changing CBN's value in the case when it deletes some CBN's ports (it causes to deleting all connectors from these ports).
If Flood sends the message in third case we get an error in Dynamo. We get no errors if Flood sends the message in first and second cases but it makes Dynamo slower.
So do not send delete connection messages in the cases above.

http://adsk-oss.myjetbrains.com/youtrack/issue/REACH-71