Fix issue 107.
Fix issue 107.

'allRefutable' was very eager to give up on the first refutation,
even if there were non-refutations present.

There are two minor problems left:
  - (regression?) we show all the refutations even if they are all the same
    where before this patch only the first got displayed (and the others
    could be potentially different(?)

  - we get "The 'backchain' bounds have been exceeded." even if I set the
    bound to 100 by ":bounds backchain 100". How does it exceed?

I also did some minor refactoring.

minad/omega,cartazio/omega