added opencl implementation of the depth processor.
cleaned up CMakeLists.txt. Removed c++11 dependency.
Parameters are now read in from the Parameters struct.
Config is read from the Config struct.
Removed unused variables from opencl code.
using found opencl library.
Get the missing cl.hpp from Khronos.org
Allow apple platforms to find the cl.hpp file
fixing compilation if opencl is not available
Merge pull request #1 from christiankerl/opencl_depth_packet_processor

Opencl depth packet processor