mods to clearinghouse.h and new messages

modified clearinghouse.h to change Motor so that is has two
constructors...one for motors with current sensing and another
constructor for motors without.  I need to test the reverse()
funtion in Motor
	new file:   messages/control_effort.h
	new file:   messages/pitch.h
	new file:   messages/plant_status.h
	new file:   messages/state_vec.h
added Position::position and used it in Motor
modified Motor.drive()

  - overloaded .drive to take a Direction::dir and pwm input
    directly without having to formulate a motorstate struct
Significant changes

  - Added a new gw::vector<class T> type that represents the
    mathematical notion of a 1 x 3 vector for holding sensor data
    from the gyro and accel.
  - Added basic vector math functions in the gw namespace to handle
    work on vectors (dot, scalar multiplication, cross, add, and
    normalize).
  - gw::vector and some of the vector math functions are a port from
    the Pololu libraries for the L3G gyro and LSM303 accelerometer.
added Pololu license to clearinghouse.h