Write LastGameStats in preview window

[Forestidia86]

Due to lack of space on smaller resolutions level information or stats get overwritten by the stats for the current game (LastGameStats), see issue #395, issue #324.

My suggestion to solve that is to write the current stats on the space of the preview window. The window has quite some space and you don't need the preview shortly after you've played the level. Furthermore there the recent stats could catch more attention I think though unsure.

[Simon]

Right; when we return from play to the browser, the preview is the least-needed widget in the main window area. (Only the title bar is less interesting at this moment.)

This is worth trying. This sounds like a comfortable solutions that doesn't re-introduce an end-of-level dialog. In a pinch, we can always reject it afterwards still.

-- Simon