Add `out` parameter to ReductionKernel call.
pass wait_for to enqueue_fill_buffer backend
skip tests unsupported by pocl
test enqueue_barrier/marker and wait_for_events
test unload_platform_compiler
Merge pull request #52 from yuyichao/master

Add some tests for wrapper backend and skip some tests that are not supported by pocl.
Minor PEP8 cleanup
Update scan ignored words list for fp64 warning fix
Merge pull request #51 from gw0/add-reduction-out-with-offset

Add `out` parameter to ReductionKernel call.
Add change remark about out parameter in ReductionKernel