ensure that repeated book1/book2 content is both latexified

[murphyk]

Some of the content in book2 ( eg ch 3 on Bayes) has identical figures to book1.
(Some of this is new content that used to be in supp2, that I moved back to book2 a few days ago).
In book1, these have been latexified, but in book2, they have not. We should not waste the latexification effort :)

Example:

[murphyk]

Another example from ch 2 (probability)