* Turns out that using gtk_widget_destroy(), the finalize handler never gets called!?
  This means we were leaking memory.
* Using g_object_unref() fixes that and the initial Scintilla patch is no longer necessary.
* There have previously been use-after-free bugs when *not* using gtk_widget_destroy().
  This has apparently been fixed in the meantime in Scintilla.

* the GObject lifecycle was violated, resulting in use-after-free scenarios

* The patch avoids all automatic scrolling consistently, including in SCI_UNDO.
  This speads up Undo (especially after interruptions).
* Also, the patch disables a very costly and pointless (in SciTECO) algorithm that
  effectively made <Ix$> uninterruptible.
* Effectively reverts large parts of 8ef010da59743fcc4927c790f585ba414ec7b129.
  I have never liked using unintuitive Scintilla messages to avoid scrolling.

* actually everything is updated to their current HEADs but the aforementioned versions are close.
* Scintilla uses threads now, so we added checks for pthread.
  To be on the safe side, we imported AX_PTHREAD from the Autoconf archives.
  The flags are kept out of the ordinary build system, though and used only for compiling Scintilla
  and for linking.
  SciTECO may also use threads, but via Glib.
* Scinterm removed SCI_COLOR_PAIR(), so we re-added it to src/interface-curses/interface.c.
* There is an Asciidoc lexer now.
* The <Ix$> interruption bug (see TODO) is not fixed by this upgrade.
  Perhaps the Mac OS version runs better now. Feedback is needed (refs #12).

* These are apparently "Microsoft DirectX Typography Services"
* patch should be contributed upstream

* mingw-bundledlls finds and copies transitive DLL dependencies.
* Like all external one-file sources, mingw-bundledlls has been copied into contrib/
  instead of adding a submodule.
  It's taken from here: https://github.com/mpreisler/mingw-bundledlls
* Packaging is more robust now if dependant DLLs are upgraded or if we
  decide to link in more statically.
  With the old scheme, we might also miss some DLL and break builds
  without even noticing it.

* This simplifies writing CFLAGS="-g -O0" CXXFLAGS="-g -O0".
* We build "release" binaries by default.
  NDEBUG will now be defined unless you specify --enable-debug.
  This enables some optimizations that have long been implemented but were never actually active:
  * SciTECO shuts down faster since it will not explicitly free memory.
    On the downside, this would complicate memory debugging with Valgrind/memcheck.
  * dlmalloc is built with -DINSECURE=1 which is supposedly a bit faster.
    Some compilers also complained about an unportable preprocessor usage which should
    now be gone.
* All CI builds are now with --enable-debug.
  This will slow them down but ensure that more code is executed and thus tested.

* the bug probably wasn't a regression compared to v0.6.4

* The default build system includes -arch arm64 -arch x86_64
  (builds for both platforms).
  These flags are apparently not supported by the SDK on the
  build server.

* saves some build time
* fixes Win32 Gtk+ builds