using default optimization level (-O1) for debug version
listener service: listen on multiple connections
(tcp4 and tcp6 or multiple devices or both)
separate different event implementations
rewirte epoll event monitor to reduce superfluous notifications
Merge branch 'epoll' into develop
reclaim resource when failed to sending it
using switch clause to ease addition of internal message type handler
move internal used definition to process.c
using monitor_t to represent monitor reference
using `source` field in message to determine where retired message come from
rewrite inter-process monitor/demonitor using message
Merge branch 'monitor_refactor' into develop
to fix bug: monitored process hold back reference to
retired supervisor process, prevent it from deleting
rewrite echo example to buffer massive write requests
Merge branch 'echo' into develop
Merge branch 'develop'