problem with enqueue_fill_image

I'm pretty sure I'm using enqueue_fill_image according to the spec:

``` python
import pyopencl as cl

#...

output = cl.Image(mgr.context, cl.mem_flags.READ_WRITE, cl.ImageFormat(cl.channel_order.RGBA,cl.channel_type.UNSIGNED_INT32),
shape = (mgr.cell_width, mgr.cell_height*2))

fill_evt = cl.enqueue_fill_image(mgr.queue,output,np.zeros((4,),dtype=np.uint32),origin=(0,0),region=output.shape)
```

I'm getting an error that clearly indicates there is something different in the expected arguments list:

```
ArgumentError: Python argument types in
pyopencl._cl.enqueue_fill_image(CommandQueue, Image, numpy.ndarray)
did not match C++ signature:
enqueue_fill_image(pyopencl::command_queue {lvalue}, pyopencl::image {lvalue}, pyopenclboost::python::api::object, pyopenclboost::python::api::object queue, pyopenclboost::python::api::object mem, unsigned long color, unsigned long origin, pyopenclboost::python::api::object region, bool wait_for=None)
```

It seems like either the reference is outdated, in which case I want to know how to actually use this function, or something in the code is incorrect. Could you look into this?

-Thanks