Gk browser editing arrays

Makes it possible to 

*add or delete one or more object in a table
*create and insert one or more objects at selected rows in array
*remove one or more objects from array at selected rows
*ditto plus delete
*move one or more objects within an array by dragging

The created objects are filled with default values set in my code. Should probably check if defaults exist for the classes and use that when possible. The logic for letting the browser produce the default values is that the user might want to customise this, and the browser user might not have access to the model classes.

I know this is a big merge, but there isn't really any good way to split it into smaller merges. I will provide a  flow chart for the actions, since each interaction involves around half a dozen methods in 3 or 4 classes.
@jpsim 
Actually, since this is an override of an NSObject method, shouldn't it be id? The context I use it is the following:

Whenever I make a change to an array I broadcast it to all open windowcontroller, and if they are displaying the same array(node), they will also perform the relevant animation. Each windowcontroller has a property displayedType, which may or may not be an RLMArrayNode, so there are two ways to test this:

1. Send isEqualTo: to something that may not be an RLMArrayNode, with the argument always an RLMArrayNode,
2. Always send isEqualTo: to an RLMArrayNode, with an argument that is mostly not an RLMArrayNode.

In 1 it will mostly result in using the isEqualTo of NSObject, which will correctly return NO because the objects are not the same as far as the inherited method is concerned, and when it uses the override it will of course work correctly. In 2 it will always use the override, hence work correctly.

But in either case I'm not sure it should only take RLMArrayNodes as arguments. Making an ìsEqualToRLMArrayNode:`method isn't a good solution either, since it will either get called on, or with, things that are not RLMArrayNodes.

I added the class test, in any case.