remove "external" dependencies

[hugoledoux]

• chap2 about acquisition
• chap7 about runoff has several links to parts of papers
• chap10 about streaming
• chap11 about visibility/LoS in a TIN

[hugoledoux]

and perhaps all figures from other books/papers? This can become an issue in the future if we want to release the book as a TUDdelft open book.

• a few in pcprocessing

[hugoledoux]

remove figures 11.7 and 11.9

[hugoledoux]

• visibility: rewrite the 2 short-ish sections that I link to?