Restructure Book

[rlanzafame]

This PR will officially update the book with the new structure, developed by @rlanzafame and @tshiya731 in early 2025.

Let's try to keep discussion on this PR limited and instead take care of that in other PR's going into the restructure-book branch.

There are a many issues that should be addressed prior to closing this PR.

Some things to think of when getting ready to publish the new structure:

• adopting versioning
• changelog
• moving repo to a different github organization
• archiving the "old" book on a different branch
• adding banner to "older book" on tudelft-citg replace old book on org tudelft-citg with a "this book has moved" book/page  #21
• checking copyright

[tshiya731]

Hi Robert, the followings are the explaination and remained questions for the commits I've made:

1. commit 'chapter-4': this chapter is the previous chapter "objects and references".
   questions needed to check: add contents into objects.md and nutshell.md; the storage of pictures in this chapter
2. commit 'chapter5-modules': this is a new added chapter from original chapter 2.1. I moved the original 2.1 into this chapter including the additional material and exericses.
   questions needed to check: add contents into .md
3. commit '.toc change': simple change about toc
4. commit 'chapter2-exercise change': in this commit i deleted the original exercises for 2.1 because they were moved to chapter 5.
   questions needed to check: the numbering of exercises became a bit weird for chapter 5

@rlanzafame