[Gecode] Important change for commiting to alternatives

[Christian Schulte]

Dear all,

I just rectified an annoying design inconsistency in the way how commit for
spaces and branchings has been handeled: for a space with n alternatives the
alternatives were referred to by 1...n (which is of course bad in a C/C++
context). I fixed it to go from 0...(n-1).

This means that you have to adapt the search engines in Alice.

Cheers
Christian

--
Christian Schulte, http://www.imit.kth.se/~schulte/