- compute re-projection of predicted position ('h') right after the
prediction step of the EKF. So it can be used for the tracking.
- created a Features_extra structure, which contains all the extra info
about the features. 'h', 'H', 'z' and if it is valid.
- use dataset from the actual drone
- OF is filtering out tracked features outside the image space
- OF is now using the predicted information of the EKF as starting point
for the OF.
- Features which have predicted a negative depth are no longer used.