Replacing camera matrix with projection matrix as LSD Slam assumes recti...

...fied input images if camera_info is given as input.

When calibration is not provided by input file but by camera_info message, the input images are required to be rectified beforehand (e.g. by ROS image_proc). As a consequence, the correct intrinsiscs are stored in P and not K. 

Tested with LSD_machine.bag and live with one of our cams.