doc: minor formatting fixes in the markdown version.
bugfix: fixed compilation warnings when ngx_devel_kit is missing in the build.
bugfix: ngx.req.set_header() did not completely override the existing request header with multiple values. thanks Aviram Cohen for the report in #314.
doc: documented the ngx.worker.exiting() API.
doc: documented the new behavior regarding zero-delay timers upon nginx worker process exiting.
doc: bumped version to 0.9.3 and also stated that we work with nginx 1.4.4.
bugfix: subrequests initiated by ngx.location.capture() might send their own response headers more than once. this issue might also lead to the alert message "header already sent" and request aborts when nginx 1.5.4+ was used.
fixed the tests for truncated subrequests to reflect the changes in nginx 1.5.3+.
fixed issues in the test suite exposed by nginx 1.5.7.
version bump.
Merge branch 'master' of https://github.com/chaoslawful/lua-nginx-module
Merge branch 'master' into socket-changes
Author: aviramc <aviram@adallom.com>

Fixed merge issue (some function that were moved to a different file became duplicate).