First polarization calculations in MAD

A new module has been added to the program MAD allowing the calculation of polarization levels in electron and positron storage rings. It is based on the program SITF developed at DESY. Its availability inside MAD offers the great advantage of allowing to use machine descriptions in MAD format, and to change single elements interactively, thus showing immediately the impact on the polarization level. Calculations are performed for thick elements, with alignment and field errors, and treat the depolarizing effects caused by quantum diffusion in energy, and by quantum excitation of vertical motion. They are based on linear spin-orbit coupling, and use a first order perturbative approach