[Ipopt] Return infeasible for inconsistent bounds?

[Tony Kelman]

Hi all,

There are 2 places in IpTNLPAdapter.cpp where an INVALID_TNLP exception gets 
thrown if a problem has lb > ub on a variable or constraint. I was finding 
Bonmin would fail to solve a pretty simple MIQP (in osil format at 
https://gist.github.com/51879c7e2cc850d95125, running via OSSolverService) 
due to this exception at an intermediate subproblem.

I have a patch to add a new exception type for this condition and handle it 
with an infeasible return status. I've opened a pull request on github at 
https://github.com/coin-or/Ipopt/pull/2 for review. Let me know if anyone 
has any input.

-Tony