HipHop improvements:

HipHop improvements:
* Added the ability to compile extensions. The build process is bootstrapped by running MediaWiki in interpreted mode. Extension setup file inclusions are slightly modified in a way that makes them register themselves for compilation. Then the same LocalSettings.php uses the compiled extension setup file when the compiled binary runs.
* Tested with Cite and ParserFunctions. The code which lets you have an extensions directory in a place other than $IP/../extensions is untested.
* Simplified WebStart.php slightly by using a custom $_SERVER variable to mark compiled mode. It will break if you don't use the supplied server.conf, but that will break a lot of things so don't do that.
* Fixed the core web entry points to include WebStart.php in compiled mode instead of interpreted.
* Made the build directory configurable. This is mostly so that I can grep the source tree without seeing loads of generated C++.
* In server.conf, added a rewrite rule allowing a /wiki/$1 article path.
* Removed server.conf log file location "/dev/stdout", breaks when you switch user
* Disable static content cache, breaks horribly when you set SourceRoot to a directory containing 7GB of files.
* Rewrote the run-server script in PHP, mostly to support the configurable build directory feature.
* Added an option to the run-server script to allow running in interpreted (hphpi) mode.