Current group in fullscreen

Add a new option "Put the current group/column/row in fullscreen".

I replaced my shell console by the powerfull Terminator console (http://www.tenshu.net/p/terminator.html) which has awesome features like the ability to split a pane horizontally and vertically and the ability to put the focused pane in fullscreen with a simple shortkey. This is quite useful in console, especially when the output of a command is really wide.

I think this ability to put a "pane" to fullscreen could be a useful feature in Sublime Text too : I develop with a 2 columns layout but I often need to focus on a single column. I can switch back to a single column layout but if I switch back to a 2 columns layout, I will have to move all files in the second group.

Actually, when I want to focus on a column, I reduce the width of the second column to the minimum but it would be easier with a simple shrotchut.