tag4: Merge pull request #56 from andreasgal/command_queue_event_fix

Cleanup wait_list and event handling for command queues and don't allocate unecessary custom events.

tag3: Merge pull request #52 from andreasgal/create-image-buffer

support buffer argument to clCreateImage

tag2: Merge pull request #49 from milhidaka/fix_vector_arg

Fix of vector argument