Breaking change: restructure pages into respective folders

[RaoOfPhysics]

The root repo is HUGE because of the various individual .md files. Can we move the files (git mv, so that all history is retained) into sub-directories?

[zee-moz]

Great idea! I agree and I've been planning to do so, but was worried about messing up the GitBook structure. I think will just require updating the index file for the GtiBook with the correct file paths... I can't do that until Monday... Can we give this a try next week? Thanks!

[RaoOfPhysics]

@zee-moz: I will take a look at it. Unfortunately, I won't know if GitBook will render it correctly until my changes are merged. :P