deleted duplicated files.
more verbose sess_stat().
headfiles for libreadline have been added.
Fixed two bugs and added a feature.

Bug 1. listmap
Bug 2. luaL_checkstring will crash when the stack frame is nil
Feature: enable_active_close is configuable.
uptime-like statistics has been added to sess_stat()
Block SIGALRM when calling epoll_wait.