* fix options stack_solve_algo={2,3,4} (closes #68)
* fix crashes for singular normalizations (closes #44) and implement decreasing cutoff
* fail for stack_solve_algo=2 under Octave (because there is no gmres function in Octave)


git-svn-id: https://www.dynare.org/svn/dynare/trunk@3279 ac1d8469-bf42-47a9-8791-bf33cf982152