NetBSD 10.0 released

Version 10.0 of the NetBSD system has been released.

The netbsd-10 release branch is more than a year old now, so it is
high time the 10.0 release makes it to the front stage. This
matches the long time it took for the development branch to get
ready for branching, a lot of development went into this new
release.

This also caused the release announcement to be one of the longest
we ever did.

As might be imagined, there are a lot of changes; see the
above-mentioned release announcement for the details.