Update vignette to mention `set_seed`.

[jlmelville]

As discussed in #40.

[eddelbuettel]

Thanks!

[eddelbuettel]

I added the also nice-to-have-in-PRs

• entry to ChangeLog
• entry to NEWS.Rd
• unit test we talked about :)
• corrected the vignette addition as the function is called setSeed() here

[eddelbuettel]

And I promptly messed up the test :-/ and did not notice locally as some tests are skipped unless opted in.

Dang.

[jlmelville]

About set_seed, I hadn't realized until I started updating it that it talks about using the AnnoyIndex C++ class directly, rather than the Rcpp wrappers, so in the context of the vignette, I think you would call set_seed. It now strikes me that it does make it less relevant to the original PR as you could always have called the original C++ code if you wanted to!

I use RcppAnnoy extensively as part of the uwot package, so I could contribute an R-specific vignette if that would be helpful.

[eddelbuettel]

That's something we may want to fix -- R users are only seeing the modulated code via Rcpp Modules.

You are unique in using the headers directly.

And mind you the vignette is titles 'annoy from c++'. Hm :) Maybe I need to revert my revert :)

[eddelbuettel]

BTW I reverted the change to the vignette.