* for 2nd and 3rd derivatives of static and dynamic model, create the sparse matrices in a more efficient way (thanks to Pablo Winant for suggesting this and providing a patch)
* this breaks USE_DLL option at order 2
* fixed bug when hessian or 3rd deriv. matrix was all zero: the matrix was not constructed at all, leading to crashes in Matlab code


git-svn-id: https://www.dynare.org/svn/dynare/trunk@2787 ac1d8469-bf42-47a9-8791-bf33cf982152