TODOs..
crypt: define ZERO_CRYPTSHA1
sec msg: --supportedNodesDir
node msg sec: purge_deprecated_dhast_tree(), badlist_neighbor(),  (purge dhash_invalid_plist)
node: let nodeIdFromDescAdv() return NULL for failures
msg sec: purge_cached_descriptions() rx_frame_description_adv()
msg node sec: deprecated_globalId_tree...
msg: rx_frame_iterate_error: less syslog
msg: tx_msg_description_request() cancel deprecated dhash