[kdevplatform] shell/workingsets: Rename the "Close" working set button to "Stash"

[Sven Brauch]

On Tuesday 01 April 2014 14:48:19 Aleix Pol wrote:
> "Hide Working Set"?
Yes, that might work. It's a bit long, but ok -- there's enough space in the 
widget anyways. I'll do that and wait for more complaints.

> I agree that all in all, it probably should be re-thought. Personally, I
> don't use the working set feature at all so I'm not the best person to take
> a decision there.
I only use it sometimes, so I'm not the best person here either. But when I 
use it, I'm often unhappy with how it works.

Greetings!