Changes

When the unit is loaded, it collects all mover desc containing all tags from the <code>desc_tags</code> property and all mover anim containing all tags from the <code>anim_tags</code> property. When the mover is generated, it randomly chooses one of the collected mover desc and then it tries to choose one of the collected mover anim which use the same model skeleton as the choosen mover desc model.  This is important because sometimes you want to have group containing models with diferent skeletons and animations with diferent skeletons. But you want only valid model anim combinations. For example group of walking men and women where men use different skeleton than women.