[Symphony] Warm starting and rhs modification

[Alexander Sviridenko]

It seems like the problem was solved. Thank you for support.

However, since I was able to use warm starting, I have a question. I'm
taking a problem and solve it. Then I'm changing rhs bounds and
resolve it and so a lot of times. But the profit from warm starting in
this case in comparison with a simple use of branchAndBound() for each
resolving is very small. And sometimes even leads to negative result
when the warm starting case works longer. Maybe you have some thoughts
about this?

Thank you.

Alexander