Use internet archive for external URLs

[yarikoptic]

urls could go away quick or not so quick but die for one reason or another.

I didn't research into some plugin or whatnot, but may be all or some of them could/should be complimented with IA links, e.g. instead of

For example, this method is now used

have

For example, this method is now used^IA

or alike?

(also might be worth promoting such a practice may be generally as an aspect of versioning references???)

[poldrack]

moved to new repo at https://github.com/BetterCodeBetterScience/book/issues