* 13 is now the oldest supported version

* You can now specify `--with-scitecodatadir` as a relative path,
  that will be interpreted relative to the binary's location.
* Win32 binaries already were relocatable, but this was a Windows-specific
  hack. Win32 binaries are now built with `--with-scitecodatadir=.`
  since everything is in a single directory.
* Ubuntu packages are now also built `--with-scitecodatadir=../share/sciteco`.
  This is not crucial for ordinary installations, but is meant for AppImage creation.
* Since AppImages are now built from relocatable packages,
  we no longer need the unionfs-workaround from pkg2appimage.
  This should fix the strange root contents when autocompleting in
  AppImage builds.
* This might also fix the appimage.github.io CI issues.
  I assume that because I could reproduce the issue on FreeBSD's
  Linuxulator in dependence of pkg2appimage's "union"-setting.
  See https://github.com/AppImage/appimage.github.io/pull/3402
* Determining the binary location actually turned out be hard and
  very platform-dependant. There are now implementations for Windows
  (which could also read argv[0]), Linux and generic UNIX (which
  works on FreeBSD, but I am not sure about the others).
  I believe this could also be useful on Mac OS to create app bundles,
  but this needs to be tested - currently the Mac OS binaries are
  installed into fixed locations and don't use relocation.

* Apparently it's not possible to run it as part of CI.

* Any memory error will let the test case fail with code 66.
* You can also call
  make check TESTSUITEFLAGS="--valgrind"
* There is no program test for Valgrind in configure.ac for the time being.
  `valgrind` must be in $PATH.
* All CI testsuite runs under Ubuntu are now with Valgrind.

* The Mac OS package for v2.1.0 actually still encodes "2.0.0".
  But I am going to ignore this. It's not worth fixing, considering the
  experimental nature of the Mac OS builds.

* This is necessary to fix the Unicode test suite on Win32,
  so I was always passing in --disable-shared manually.
  It's easy to forget though when building from scratch.
* We don't currently install any (shared) library, so this is safe
  on all platforms.
  In fact on all other platforms, libtool detects that and doesn't
  generate wrapper binaries in any way.
  Only on win32 it's apparently buggy.

* character-based model, avoid mentioning "ASCII code"
* added "0EE" example
* should be built with pdfmom, so it's built with gropdf