#1 Verify Server response packets

[Markus Ansmann]

Currently the LabRAD Manager always forwards Server responses to the specified Clients without checking them for validity.

Clients should be able to know what responses to expect based on the information published by a Server about its interface. Currently, this is not ensured by the Manager.

The validation should include the following:

- Verify correct layout of response packet: One response record for each request record, preserving the order; errors terminate a packet

- Verify response records: If possible response type tags were given, enforce them; also allow for error records

- Block responses to requests that have been cancelled: If a client disconnects, don't send responses to the next client who happens to get same ID