Change the row bound rounding rule to tolerance based when set up the LL/SL problem

[yuxies]

In the function `setUpModel()' in MibSBilevel:

• remove the rounding on the original row bounds b^2;
• add a tolerance check before rounding values b^2 - A^2 x.

[tkralphs]

I don't think we even need rowLb and rowUb now. About all that happens is that we copy from one array to another, possibly negating the values. But then that new array is only used once after that and we could easily just have origRowSense[index1] == 'G' ? origRowLb[i] : - origRowLb[i] instead of rowLb[i]. What do you think?

[yuxies]

We could do that, except for the initial setup.

For newOSI, we still need rowLb and rowUb to store the rearranged lower level row bounds and pass them to loadProblem(*newMat, colLb, colUb, objCoeffs, rowLb, rowUb). Once the Osi is initialized, we can switch to using condition checks on origRowLb and origRowUb when iterating over lower level rows. Some of the loops in setUpModel() that process lower level rows can also be consolidated and cleaned up.

But since we have to use rowLb and rowUb for the initial setup, it may be simpler to continue using them to keep the code more consistent and easier to read.

[tkralphs]

OK, I see.