mod_lua: Add a lot of core httpd/apr functionality to mod_lua

(such as regex matching, expr evaluation, changing/fetching server configuration/info - see docs for a complete list).
This also includes a bunch of automatically scraped functions, which may or may not be super useful.
Comments appreciated as always, especially on the more hacky bits.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1420377 13f79535-47bb-0310-9956-ffa450edef68