Simple implementation of bitonic sort in OpenCL.

• To build, run on command line:
  g++ -o bitonic_sort -I<location to OpenCL headers> -L<location to OpenCL library> bitonicSort.cpp -lOpenCL
• Profiling best done using a profiler. To enable profiling, make changes in the createCommandQueue function as follows:
  34: queue = clCreateCommandQueue(context, device_id, CL_QUEUE_PROFILING_ENABLE, &t_err);