New standard linked list to use, rather than adhoc SignKeyList or TCPFwdList
--HG-- branch : agent-client extra : convert_revision : 5465e639cc3f5ee0c6c55f0de6e7b6d5a8769da3
--HG-- branch : agent-client extra : convert_revision : 5465e639cc3f5ee0c6c55f0de6e7b6d5a8769da3