This cleans up the constructor methods for the OpenCL wrapper
classes and unifies the API used for creating a wrapper class
object from the underlying OpenCL objects.
Now, every wrapper class has a constructor taking the OpenCL
object and an optional boolean retain parameter which indicates
whether the constructor should increment the reference count.
This remove the enqueue_wait_for_event() method from the
command_queue class as the clEnqueueWaitForEvents() function
has been deprecated in OpenCL 1.2.
This moves the unload_compiler() method from the system class
to the platform class. Also changes the method to use the
clUnloadPlatformCompiler() function instead of the deprecated
clUnloadCompiler() when compiling with OpenCL 1.2.
This moves the get_extension_function_address() method from
the system class to the platform class. Also changes the method
to use the clGetExtensionFunctionAddressForPlatform() function
instead of the deprecated clGetExtensionFunctionAddress() when
compiling with OpenCL 1.2.
This implements the merge() algorithm which merges two
ranges of sorted values into a single sorted range.
The current implementation uses a simple serial merge
algorithm. A GPU optimized version is coming soon.
