port a196a31c4435c865580c28ba87a1c309fd52fe8a from Pd-l2ork: updated closebang and initbang help files

*updated message-help.pd to reflect the new $0 functionality

(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

added local version of the docs due to increasing number of local changes that make it difficult to sync with external