Add helper functions which helps do less typing.
When add the declare node, now the view will be inserted.
Remove some un stable or not must features, make the library do what it should do. Add name to NSAssert message for better debuggability.

setupViewTree and updateViewFrame are 2 mainly used api, one to setup the view tree, which should be called in viewDidLoad or init. updateViewFrame do layout stuff and should be called in viewWillLayoutSubview or layoutSubView.

Note: Some api removed, it is not the time to take the burden of compatibility. Just make the lib easy to use.