M-M.E.S.S. 3.0 Introducing Krylov subspace methods

Added

Sparse-dense Sylvester solver, see mess_sylvester_sparse_dense.
Krylov subspace projection methods for Lyapunov equations and AREs using extended and rational Krylov subspaces, see mess_KSM, as well as demonstration examples in KSM_FDM, KSM_Rail.
A new logging system allowing to print messages to both console and files, and switch between various output file formats. See mess_log_*.
mess_tf_plot as unified backend for mess_sigma_plot, mess_Frobenius_TF_errorplot
mess_version a function to get the current version of M-M.E.S.S.

mess_galerkin_projection_acceleration has been replaced by mess_solve_projected_eqn, which now covers both the acceleration case and
the case of projected equations in the context of mess_KSM.
eqn.st and eqn.nd from DAE usfs are now unified and called eqn.manifold_dim everywhere.
the LDL^T ADI for Lyapunov now expects W T W^T rather than G S G^T as the constant term. Consequently, eqn.S and eqn.G are now called
eqn.T and eqn.W.
missing demonstration models are now loaded from the web on user request. The first run with a model may, thus, need to be interactive
to confirm the download request.
usfs have been optimized further to not use unnecessary hidden data.
mess_lrnm, and mess_lrradi now require eqn.R and eqn.Q to be set in LDL^T mode.
operatormanager now has a mandatory pass-through argument opts for correct logging.

many functions did not warn users about non-convergence
minor bugs in DRE methods were addressed
get_ritz_vals usfs and mess_para behavior has been unified
removed dead code in mess_lrnm
lyap in Octave and MATLAB had different behavior which is now properly wrapped to give consistent results
BDF methods of higher order now use lower order methods with smaller step sizes for a successive wind-up procedure to guarantee the expected order of convergence.
exact line search in mess_lrnm now uses a more expensive, yet far more numerically stable, way to compute the relevant norms.

all functions in the mor folder are not going to be maintained in future releases in favor of using M-M.E.S.S. as the sparse solver
backend for MORLAB in their version 6.0 and newer.