Make the series Sobel algorithm the same as the parallel

To get an accurate comparison of time, the same implementation of the
Sobel algorithm should be used both in series and in parallel.
Change kernel name
Use shared memory with OpenCV. Also wait, but don't flush

The IplImage data is now in shared memory, so there is no need to copy the
memory into and out of the buffers into OpenCV objects.

Also, the clwait call is now used instead of the clflush call.