If a load fails then we won't have any features, but we also won't
try and load them again for any part of that area because the bounds
tell us we have already loaded them. So clear the bounds in order
that reloads will be triggered.
Make all attempts to get a URL for an image go through a single
routine, OpenLayers.Util.getImageLocation, which is given the actual
image name.
This allows users to replace that routine with an enhanced version
which can rewrite the full URL, for example to go through the rails
asset pipeline when using OpenLayers with rails.
Give the TransformFeature control an irregular mode where dragging a
handle just extends that side rather than growing the shape symmetrically
about the centre.
Tom Hughes