bugfix: inlined Lua code snippets in nginx.conf failed to use the Lua…

… source checksum as part of the Lua code cache key. thanks Oleg A. Mamontov for the report in openresty#1428.

Fix openresty#1428.

feature: implemented a new 'lua_sa_restart' directive, which sets the…

… SA_RESTART flag on nginx workers signal dispositions.

doc: updated the docs to reflect the change that we now no longer sup…

…port the standard Lua 5.1 interpreter in this module. also recommended OpenResty's LuaJIT branch version instead of the stock LuaJIT.

typo: fixed a debug log in access and rewrite handlers.

Signed-off-by: Thibault Charbonnier <thibaultcha@me.com>