-Added what Zack wrote for his chapter.
-Fixed and added a lot of things here and there.
-Still missing some things, yet not that much.
-A lot of images are still not included, as I don't have those, yet mention where these should go.
Update chapter.md

Final additions of last sections.
3d matrices, editing changes
deeper FFT explanation, more tweaks based on feedback
finished 3d Matrices
Merge branch 'master' of github.com:openframeworks/ofBook
Merge branch 'master' of github.com:openframeworks/ofBook