removed dead code found by Simon Liu.

now we call ngx_http_lua_socket_finalize in cosocket:setkeepalive() t…

…o help buffer reuse.

optimize: now ngx.log is much faster when the log level argument is l…

…ower than the actual error_log level specified in nginx.conf. thanks Matthieu Tourne for providing the patch.

bugfix: cosocket connections from the connection pool might lead to s…

…egfaults if it is not used immediately. thanks xukaifu for reporting this as github issue openresty#108.

updated docs to reflect recent changes (documented the ngx.HTTP_OPTIO…

…NS constant).

bugfix: certain compilers might complain about missing declarations f…

…or types like int8_t. now we explicitly included stdint.h. thanks runner-mei for reporting it in github issue openresty#98.

cosocket: various optimizations in timeout handling. this gives about…

… 2.5+% performance boost in some benchmarks using lua-resty-redis and lua-resty-mysql.

updated docs to reflect recent changes.

fixed a coding style issue: we did not declare C variables at the beg…

…inning of the current code block in ngx_http_lua_del_thread, reported by runner-mei in github issue openresty#93.

updated docs to reflect recent changes.