React prototype

This is a branch that creates a view with React components. The App component contains an AST editor and a Graph component. A Graph component receives a dummy model (a simple wrapper around an AST) and renders a set of Node components. A Node component is a rectangle of a constant size and a given position. Dragging a Node element changes the node's position in the model. That change causes the view to re-render from the App component down.
I don't want to remove this, as @MorganCabral says that it serves a role as a piece of boilerplate. I'd prefer to uncomment it once we find that file.