Made several important updates.

- Changed the name and description of the 3rd argument in
CL_Kernel::SetArg(cl_uint, const void*, cl_uint) to be more descriptive
of its actual purpose.
- Modified how the local work size of CL_Kernel
is handled; now, simply set each dimension to 0 to have OpenCL determine
the correct work load per group (equivalent of passing in NULL for the
local work size in clEnqueueNDRangeKernel()).
- Updated README's Roadmap.
- Updated opencl_test's SConstruct to reflect the changes made prior to
CLcpp's SConstruct.
- Updated CLcpp's Visual Studio projects.