new class: CertificateManager
new class: ServerConfig
change the naming rule
use new configuration/certificate management classes instead of old ones
improve error handling: when closing socket/acceptor, the callback registered will still be called, so we should check if the socket/acceptor has been closed in the callback
enhance log for client/server connection mapping
bugfix: we should reset the message complete flag if a connection is to be reused
bubfix: if a connection is reused, we should cancel the running timer on it
update todo
update todo
fix crash: do NOT erase an element without changing the iterator in looping a STL container
improvement: canonicalize the uri