Today I have elapsed some hours for searching an efficient spline toolkit, that allows usage of 2nd order (quadratic) splines. The was some compiling problems with module spline from scipy.sandbox, only some minutes ago I have installed it. Tomorrow I shall learn how it works (i.e. read documentation).
I have uploaded scanned book "Linearisation method" by Ukrainian academician Phenichniy: now it's available here (in russian, I have no English version)
I decided to name the new constrained solver "lincher" - LINearisation solver that had been written in CHERkasy town, Ukraine. Some solver code has been added to svn.