openCV cvGetReal2D

Hey folks.

I’ve been playing around with the takashi’s OpenCV bits for optical flow.

When calling cvGetReal2D, as mentioned in http://forum.openframeworks.cc/t/opencv-optical-flow/367/12, I was originally getting errors because vel_x & vel_y are private. I made them both public in ofxCvOpticalFlowLK.h and things seem to be fine.

Any reason I should not change this, or is there some smarter way to sidestep this?