isTraining -- Check if a member is on a fleet's training staff.
This function checks if the member with id $pin is either the TCO or TXO of the fleet with id $fID. It returns true if the member is the TCO or TXO, and false otherwise.
This function returns false on failure.
isTraining (1, 2) /* Returns true if member with id 2 is the TCO or TXO of the fleet with id 1. Returns false otherwise. */