Core API (see Database, DB and Query).

### Database

Provides the main API for fetching and persisting beans. We can obtain the "default database" via `DB.getDefault()` or just use methods on DB.

    {@code

    // Example find by id

    Order order = DB.find(Order.class, 10);

    // Example save

    Customer customer = DB.getReference(Customer.class, 42);

    Order newOrder = new Order();
    newOrder.setStatus(Order.Status.NEW);
    newOrder.setCustomer(customer);
    ...

    DB.save(newOrder);

    // Example: Eagerly fetching associations

    // fetch Customer 42 including their billing and shipping addresses
    Customer customer = DB.find(Customer.class)
    		.setId(42)
    		.fetch("billingAddress")
    		.fetch("shippingAddress")
    		.findOne();

    Address billAddr = customer.getBillingAddress();
    Address shipAddr = customer.getShippingAddress();

    }