show() regressions

[colah]

In the module lucid.misc.io.showing:

• No support for w to specify output width. showing.image() and showing.images() take w arguments but the don't do anything. showing.show() does not take a w argument.

  To fix this, _image_url() should probably take a w argument that causes appropriate zooming if set.

• showing.show() takes a domain argument, but on the images() path it has not effect.

  This is simply because images() doesn't pass domain through to _image_url():

  url = _image_url(array)