Modified vision software to store Kalman filter inputs and outputs to
KF_Debug.txt. Also, added SIGINT signal handler (should be incorporated in
future revisions of flight software). Headers for KF_Debug.txt are as
follows:

time (s) |              Inputs              |              Outputs              |
    t      dx  dy  dz  droll  dpitch  dyaw    dx  dy  dz  droll  dpitch  dyaw