added pure C API for ngx.md5, ngx.md5_bin, ngx.sha1_bin, which is expected to be used with LuaJIT FFI (or lua-resty-core in particular). such API can be excluded by specifying the C macro NGX_HTTP_LUA_NO_FFI_API.
feature: allow injecting new APIs into the "ngx" table.
bugfix: failed to compile when SHA1 support is missing. this regression had appeared in cea321f7f9e2614c9e0932e367d15502507fa7e9.
feature: added pure C API for ngx.encode_base64 and ngx.decode_base64, which is expected to be used by lua-resty-core and etc.
feature: added pure C API for ngx.escape_uri and ngx.unescape_uri, which is expected to be used by lua-resty-core and etc.
Merge remote-tracking branch 'origin/master' into ffi
Merge remote-tracking branch 'origin/master' into ffi
Merge remote-tracking branch 'origin/master' into ffi
Merge remote-tracking branch 'origin/master' into ffi
Merge remote-tracking branch 'origin/master' into ffi
bugfix: ngx_http_lua_ffi_escape_uri did URI unescaping instead of URI escaping.
feature: added pure C API for ngx.re.match, which is expected to be used by lua-resty-core and etc.
added custom test scaffold t::TestNginxLua which subclasses Test::Nginx::Socket. it supports the environment TEST_NGINX_INIT_BY_LUA which can be used to add more custom Lua code to the value of the init_by_lua directive in the nginx configuration.
Merge remote-tracking branch 'origin/master' into ffi
Merge remote-tracking branch 'origin/master' into ffi
Merge remote-tracking branch 'origin/master' into ffi
feature: added pure C API for ngx.re.sub and ngx.re.gsub, which is expected to be used by lua-resty-core and etc.
Revert "bugfix: use of LuaJIT FFI when disabling the Lua code cache would lead to LuaJIT GC assertion failures like "g->gc.total == sizeof(GG_State)" because we unloaded the standard "ffi" module. thanks Ron Gomes for reporting this issue."

Preventing unloading "ffi" does not reallys solve the issue here because
we can end up with FFI ctype redefinition errors.

This reverts commit b3218be26612282109897651ed5ccd4ab18a9e06.
tests: replaced the domain name "direct.agentzh.org" with "agentzh.org".
fixed failing test cases to reflect the multi-value header change in nginx 1.4.1.