minor updates in lincher

I have committed some changes that allow NLP solver lincher (Python-written, BSD license) to solve problems where no other constraints than box-bound ones are present. Also, lincher doesn't require any QP solver for the case (currently the only one connected is CVXOPT one). However, specialized solvers (connected to openopt) like scipy_lbfgsb or tnc or ALGENCAN are usually much more faster.