Fix problem with autocomplete which closes when mouse is used.

Hi Marijn,

I have already (but not every time-() the problems with the completion which closes when I use the mouse (click on scrollbar or inside the list) (see https://github.com/marijnh/CodeMirror/issues/1264). 

To have every time the bug, you can change the timeout like this : 

--------------------------------------------------------------------------
  function onBlur(){ closingOnBlur = setTimeout(close, 1); };
--------------------------------------------------------------------------

So I send you a (simple patch) which fix teh problem. The basic idea is to ignore the onBlur when mouse is inside the completion list.


Regards Angelo