port from pd-l2ork git: 1e9d44635b9e6e8030f7b3efdeb0f1ddfbd95860

(manually ported)
*added @pd_help in addition to the existing @pd_extra that can be used for paths
*made pddplink capable of parsing @pd_extra and @pd_help
*updated cyclone help files to make advantage of the @pd_extra/@pd_help paths in order to reference global help file documentation