Clean up DeadCScroll

[ISSOtm]

• Fix relative links (e.g. to the LICENSE file)
• Turn non-code blocks into SVGs
• Rework parts that only really made sense when it was hosted in a GitHub repo (e.g. link to a bundle of the files?)
• Point any reference to the code files to https://github.com/gbdev/DeadCScroll

[avivace]

Fix relative links (e.g. to the LICENSE file)

On it

Rework parts that only really made sense when it was hosted in a GitHub repo (e.g. link to a bundle of the files?)

I added a link at the top of the page saying "Files related to this tutorial can be found here." linking to the folder dedicated to the tutorial I created here.

[ISSOtm]

I noticed, but the wording of later sections (such as "a GNU makefile is provided") imo don't mesh well with the new organization.