Run this command across the source:
perl -pi.bak -e 's/(20[012][0-9])-20[12][012]/$1-2023/g' `git ls-files`
and remove changes to po{,-docs}/*.po{,t} (these will be regenerated
later when we run 'make dist').
This brings libguestfs into line with other projects which have a
separate include/ directory for the public header.
It's also the case that <guestfs.h> has never particularly belonged in
the lib/ subdirectory. Some tools add -Ilib/ but they only need
<guestfs.h> and not any other headers from that directory, and
separating out the public header allows us to clean those up. This is
certainly the case for examples, and some language bindings and some
tests.
In future I'm hopeful we can use this as the basis to tease out other
dependencies, as a prelude to separating them out from the repo.
