bug#9054: 24.0.50; show source in other window

[martin rudalics]

> Mine is similar; but after I have used my own patch for two days now, it is
> actually convenient to use it as a source browser. Especially since you can
> scroll it from the source window, and you can also click in the source code in
> help buffer itself, C-h f or C-h o, and it will open under the mouse in the 
same
> window and I can switch back and forward. It is almost in a way more 
convenient
> than jumping in source files.

I just did C-h f whitespace-display-window, from there went to that
function's source and added a doc-string for it.  Displaying the source
in the help window would have been merely distracting in this scenario.

martin