New release R20170626

Believe it or not, a large test harness is run before shipping…

Fix for crashing IPOPT (bug introduced in last release)
Fix for failed options in CPLEX in pre-2016 MATLAB versions (bug introduced in last release)
BMIBNB behaved strangely on problems with binary variables if MOSEK was used as lower solver
Improved robustness of envelope approximator for functions with infinite gradients in BMIBNB
Fixed bug in sign (operator could never take the value 0)