* Add ability to force the size which an image node is rendered.
* Add unit tests for forced scaling.
* Whoops, need results!
* Round forced scaling.
* Check size of contents too.
* Remove unnecessary container node.
Using Objective-C attributes, in this case `unavailable`, we can hide
unsupported APIs at compile time instead of detecting and warn about it
at runtime with a set of asserts.
ASImageNodeTint is inflexible (your options are "no tint" and "use
`[UIColor grayColor]`") and needlessly complicates the ASImageNode
implementation. Use ASImageNodeTintColorModificationBlock() instead.
Closes#383.
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.
Rename the ASDisplayNode property to match its _ASDisplayLayer
counterpart -- `displaySuspended` is more succinct and is a more
plausible name for a Cocoa BOOL property.
Summary:
* Fixes#3
* Ordering: atomicity, then [optional] readonly, then value semantics (retain/copy/assign)
* Removed redundant `readwrite`
* No spaces between "getter = name" ("getter=name" instead)
* Property method overrides renamed as well
* self.isBlah, while technically not entirely correct, still resolves to [self blah], so left alone (@kimon had advice on this sort of naming issue last summer), and largely inconsequential
Test Plan:
* Compile and run
