Proper reviews

[stefan-hoeck]

@nmccarty I just saw that you started rearranging the structure of this project (probably because this is necessary to get the mdbook to build), but also to rephrase larger chunks of the early chapters. While I really appreciate the work you put into this, please do not push to the main branch directly but go via proper pull requests.

I'd also prefer it, if we could separate the restructuring of the project from changes to the content as much as possible. Finally, changes to the content should be properly reviewed, to make sure that the original intent of a section or exercise is not lost, but also to avoid adding new typos or other inconsistencies.

[stefan-hoeck]

After having a closer look, I suggest to undo the Edit chapter 1, Edit chapter 2, and Edit chapter 3 commits, and resubmit those as pull requests that get properly reviewed. While these commits fix and clarify quite a few things, they also introduced some new typos and sentences with words missing.