Add "Show output in tab" icon

@rgbkrk
I was thinking if that's a good idea to have an additional icon in output pane header, which will open output in separate tab. That way we will allow users to view (optionally) their output in full-scale atom editor, allowing them to search/edit/save/etc.

Let me know if that's a good idea and I'll implement, if not - I'll continue with other issues resolving.