RobotBuilder was designed with the naming conventions delineated here:
https://wpilib.screenstepslive.com/s...s#!prettyPhoto
In particular, since your motor class is lower case rather then first letter upper case, it's trying to declare an instance variable with the same name as the class. Delete the motor.cpp and .h and change your subystem name to Motor and clean and rebuilt and it should work.
In general, motor is probably not a good subsystem name. It should be tied to something unique and memorable piece of your robot, like DriveTrain, Arm, Stacker, or something like that. More ideas here:
http://wpilib.screenstepslive.com/s/...ed-programming