Updated README.md

Made the README a whole lot more linear.  Also added a sort of FAQ.
I went over this with Lluixhi yesterday, and he agreed with the change.  He also thinks that we should start working on the Github wiki again though (would be nice to link the FAQ there).

Links have been shortened drastically and are now relative (meaning that if you're on a fork, the link will take you to that fork's README, not the official one).