[API Review] Property and expression conversion methods

[Richard Bair]

> public ObjectExpression<Double> asObject();
> public ReadOnlyObjectProperty<Double> asObject();
> ObjectProperty<Double> asObject();
> 
> public static <T extends Number> DoubleExpression doubleExpression(ObservableValue<T>)
> public static <T extends Number> ReadOnlyDoubleProperty readOnlyDoubleProperty(ReadOnlyProperty<T>);
> public static <T extends Number> DoubleProperty doubleProperty(Property<T>);

I wonder if we ought not use a consistent naming here, such as asObjectProperty and asDoubleExpression? Also should it be asFoo or toFoo? Is there a precedent?

Richard