Made context menu actions available on combo editor items...

Hi Diego,

This is quite a big change.  After my latest pull from your master branch, I saw that you changed the way the combo editor items are displayed and I am not sure, but the impression that I got was that you went that route primarily to make it possible to close files from the dropdown (this may or may not be the case obviously and is purely an assumption).

Anyway, I thought that, if that was what you wanted to achieve, I could perhaps propose an alternate route, which is what I did here.  With the changes in this branch, context menu actions become available on the combo box's items themselves and all file actions that you could originally trigger from the combo editor's context menu are now available on the individual items as well.

In order to make the changes more sensible, I have split the functionality into two paths, the one deals with file specific context menu actions and the other deals with the original context menu actions.  What this means is that, when the user calls up the context menu on the combo editor itself, the original context menu is displayed (with a slight reshuffle of the order of the actions) and when the user invokes the context menu on the individual editor items, the file specific actions are displayed.  

Let me show you some screenshots to make more sense of this.  First of, the original context menu, note that the editor options are to split vertically and horizontally as well as to undock and that these items aren't grouped together:

![before](https://f.cloud.github.com/assets/2462770/2494253/3df5dcc2-b2bd-11e3-9dee-46589e81a9ea.png)

The main context menu after the reshuffle now has all three of these items grouped together at the bottom of the context menu:

![after](https://f.cloud.github.com/assets/2462770/2494217/9067829a-b2bc-11e3-9629-7f92ba903435.png)

And when invoking the file specific context menu, these three actions are no longer available to the user:

![filespecific](https://f.cloud.github.com/assets/2462770/2494222/a992c8ec-b2bc-11e3-99a9-14534dd7f6f5.png)

Please let me know if you are interested in this branch and/or if you would like me to rework anything, etc etc.  I urge you though to grab this file and take it for a spin just to see what I mean with this massive essay :)