DUI: key navigation. Part 5(or 2.1)

State: _High_
Yellow navigation is from [first PR](https://github.com/Benglin/Dynamo/pull/123).
Light pink is from [second PR](https://github.com/Benglin/Dynamo/pull/127).
Red is from this PR.
This PR makes navigation between methods inside class possible.
![image](https://cloud.githubusercontent.com/assets/8158404/4735063/e9b1c4f2-59db-11e4-9e88-bc013cfd89be.png)
Reviewers
@Benglin ,@vmoyseenko, please take a look.

Link to YouTrack:
[MAGN-5075](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-5075) DUI: On Enter for Class the list of members should be collapsed / expanded.
Rephrase this (if I have understood it right);

```cs
// As focus moves within the class details, class button gets selected which 
// triggers a selection change. During a selection change the items in the 
// wrap panel gets reordered through "OrderListItems", but this is not always 
// necessary. Here we determine if the "ListView.SelectedIndex" is the same 
// as "currentSelectedIndex", if so simply returns to avoid a repainting.
```

That brings me to another question... can we not check this instead of creating ```currentSelectedIndex```?

```cs
if (e.AddedItems.Count == 0 && (e.RemovedItems.Count == 0))
    return; // There is no real change in selection.
```

Can you please try to see if this works? If it does, then we can remove our ```currentSelectedIndex```.