[Effen] Move README.md to correct directory

sky/framework/README.md

 Effen (fn)
 ===
 
 Effen is a prototype of a functional-reactive framework for sky which takes inspiration from [React](http://facebook.github.io/react/). The code as you see it here is a first-draft, is unreviewed, untested and will probably catch your house on fire. It is a proof of concept.
 
 Effen is comprised of three main parts: a virtual-dom and diffing engine, a component mechanism and a very early set of widgets for use in creating applications.
 
 The central idea is that you build your UI out of components. Components describe what their view should look like given their current configuration & state. The diffing engine ensures that the DOM looks how the component describes.
 
 If you just want to dive into code, see the `sky/examples/stocks-fn`.
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 The answer that many people don't get is that there are really two logical types of builds: (1) When underlying model data changes: This generally requires handing in new data to the root component (in Effen, this means the `App` calling `setState` on itself). (2) When user interaction updates a control or an animation takes place. (1) is generally more expensive because it requires a full building & diff, but tends to happen infrequently. (2) tends to happen frequently, but at nodes which are near the leafs of the tree, so the number of nodes which must be reconsiled is generally small.
 
 React provides a way to manually insist that a componet not rebuild based on its old and new state (and they encourage the use of immutable data structures because discovering the data is the same can be accomplished with a reference comparison). A similar mechanism is in the works for Effen.
 
 Lastly, Effen does something unique: Because its diffing is component-wise, it can be smart about not forcing the rebuild of components which are handed in as *arguments* when only the component itself is dirty. For example, the `drawer.dart` component knows how to animate out & back and expose a content pane -- but it takes its content pane as an argument. When the animation mutates the inlineStyle of the `Drawer`'s `Container`, it must schedule itself for rebuild -- but -- because the content was handed in to its constructor, its configuration can't have changed and Effen doesn't require it to rebuild.
 
 It is a design goal that it should be *possible* to arrange that all "build" cycles which happen during animations can complete in less than one milliesecond on a Nexus 5.