It is a fork of Bitcoin Core with some features but it hard-forked which makes it kinda-altcoin.
BitcoinXT didn't hard fork, nor will it deploy a hard fork automatically in it's current release. The link at the beginning of the thread point to Gavin's development repository; the patch is not merged into the official maintained by Mike. There is no pull request. It's probably not even ready for serious testing, yet.
So please calm down and wait at least until Gavin thinks the code is ready.
What about these? Sorry, I am not a computer geek.