Fix casstcl_future_command_to_futureClientData
Fix casstcl_future_command_to_futureClientData

It returns NULL if it can't look up a future.  The previously improper use of the function caused a null pointer dereference if the lookup failed.

flightaware/speedtables,flightaware/speedtables,flightaware/speedtables,flightaware/speedtables