Add ability to merge incoming order book data into the component.

[brian-mcallister-lab49]

Expose functions to help add a price update into the order book. Something like (book: Book, update: BookUpdate) => Book, but possibly a class to maintain the book prices in a tree for efficient insert and deletes. See bintrees, and the RBTree.

This could also be written as a hook.

Here's a rough example of what this might look like:

import { OrderBook, mergeUpdates } from '@lab49/react-order-book';

const MyComponent = ({ bookData: Book, bookUpdate: BookUpdate }) => {
  const book = mergeUpdates(bookData, bookUpdate);

  return <OrderBook book={book} />; 
}