Use std::pow, update README, roll minor version (closes #64)

[eddelbuettel]

This corrects #64, and while at it, adds Ivan to the README and rolls the minor release.

We can probably just relabel this as is as 0.2.5 -- or is there something else worth sweeping up now?

[ilyaZar]

Regarding version incrementing:

I have no idea how the standard, or this particular project policies are regarding incrementing. If it's common practice to increment in these cases, and it's not too small a change to justify an increment, sure, 0.2.5 sounds good!

[eddelbuettel]

Yes the only rule is that there are no rules.

CRAN lets us do "whatever". Adam and I are card-carrying members of the "GNU" generation where things like compilers, editors, and even Linux kernels -- or entire statistical languages and environments -- commonly go by "a.b.c". It did occur to me this morning this is as good a candidate for a "patch release 0.2.4.1" as ever -- but then I reminded myself that there is value in consistency.

But we could go either way. No strong feelings.

[adamjohansen]

Thanks for catching this.

[adamjohansen]

We have 0.2.4.1 in DESCRIPTION at present, which is fine with me and seems fairly logical -- although ending up with anything more convoluted (0.2.4.1-pl65, anybody?) might be overkill. But no strong feelings either way.

[eddelbuettel]

Ah yes but that 0.2.4.1 is really only temporary esp as there are now services autobuilding binaries (https://r-universe.dev) so it is preferable to make these distinct. (It's complicated, I think overall r-universe is helpful but not distinguishing more clearly between CRAN and "other builds is not ideal -- so I try to increment at GitHub too.)

I'll upload later todat as 0.2.5.