nloptr provides an R interface to NLopt, a free/open-source library for nonlinear optimization providing a common interface to a number of different optimization routines which can handle nonlinear constraints and lower and upper bounds for the controls.
No worries. You've done a lot! I hope I did not miss some places but I think I am there. One more reverse dependency broken and I'll submit the release.
when using deprecated behavior. Closes #159.