bugfix: we might try sending the response header again in ngx.exit() when the header was already sent.
fixed incompatiblities in nginx 1.5.8 which breaks the resolver API in the nginx core.
updated the tests to reflect recent changes in ngx.exit().
feature: allow use of ngx.exit() in the context of header_filter_by_lua*. but in this context ngx.exit() returns immediately.
reindexed test file t/041-header-filter.t.
minor debugging log tweaks.
bugfix: coroutines might incorrectly enter the "dead" state even right after creation with coroutine.create(). thanks James Hurst for the report.
optimize: we no longer clear the lua_State pointers for dead "light threads" such that their coroutine context structs could be reused by other "light threads" and user coroutines.
bugfix: we did not set the shortcut fields in r->headers_in for request headers in our subrequests created by ngx.location.capture*(). thanks Aviram Cohen for the original patch in #318.
tweaked a test case that could fail randomly on slow machines.
Merge branch 'master' of https://github.com/chaoslawful/lua-nginx-module
Merge branch 'master' into socket-changes
Fixed typo.