[mlpack] mlpack 3.4.2 released

[Ryan Curtin]

Hello everyone!

Today I released mlpack 3.4.2, but I did it a little bit differently
than in the past.  I just clicked a button!  In the past releases have
required a lot of manual effort on my part, but over the past several
months we've worked on automatic release scripts for ensmallen, and
today I adapted and used those for the first time with mlpack.  So, when
I merged https://github.com/mlpack/mlpack/pull/2681, basically
everything was done automatically, except this email. :)

If you want the new version, it will be available in your package
manager soon (hopefully), or you can download the source here:

  https://www.mlpack.org/files/mlpack-3.4.2.tar.gz

Be sure to check out the website https://www.mlpack.org/, which now has
integrated notebook support so you can play around with mlpack without
even downloading it!

Anyway, here's a changelog:

  * Added Mean Absolute Percentage Error.

  * Added Softmin activation function as layer in ann/layer.

  * Fix spurious ARMA_64BIT_WORD compilation warnings on 32-bit systems
    (#2665).

They're pretty minor changes, but it is a patch release, after all.

The next release of mlpack will be mlpack 4.0.0 (unless of course we
find some critical issue that's easy to backport), and this will remove
boost::serialization, replacing it with the cereal serialization
library.  We're hopeful that this will improve compilation times and
make the dependency footprint of mlpack a little bit lighter.  You can
see some of the changes we're planning on merging into 4.0.0 here:

  https://github.com/mlpack/mlpack/milestone/30

Anyway, I hope the new release is useful for you, and as always, if you
encounter any issues please feel free to post an issue on Github or get
in touch via the chat channel, or even join the video meetup.

Have a great day!

Thanks,

Ryan

-- 
Ryan Curtin    | "That rug really tied the room together."
ryan at ratml.org |   - The Dude