A go at making the depth_packet_stream_parser better.

Iterates through all bytes to find footer but copy data in chunks.
Doesn't use additional working buffer.

I tried to find out why I was getting a lot of as show here https://github.com/OpenKinect/libfreenect2/pull/72#issuecomment-59805519 .

And I found out that its probably not about the code, but rather a hardware/software issue of my dell Precision m6600, with a Renesas USB 3.0 controller not being able to process and acquire all the data that the Kinectv2 sends out.

Also when data is transferred using ISO-mode, the packages are not guaranteed to be received either in order or at all.

I don't have any measures if this is faster/better than the previous, but it avoids using the extra working buffer.