ASDisplayNodes now have an overidable method -placeholderImage that lets you provide a custom UIImage to display while a node is displaying asyncronously. The default implementation of this method returns nil and thus does nothing. A provided example project also demonstrates using the placeholder API.
Use ASBasicImageDownloader by default -- you can now do...
ASNetworkImageNode *imageNode = [[ASNetworkImageNode alloc] init];
imageNode.URL = [NSURL URLWithString:@"..."];
[self.view addSubview:imageNode.view];
...and it'll do the right thing.
Working-range-driven image loading.
(Note that ASNetworkImageNode and ASMultiplexImageNode haven't yet been
updated to work with the new `-reclaimMemory`-based working range
system, so this doesn't quite behave correctly yet.)
