* It is even more robust now and does not remove the large document
  optimization.
* And actually while problems were caused on NetBSD 10 on ARMv6,
  this likely wasn't a problem on all NetBSD ports and wasn't
  restricted to NetBSD. At the very least Haiku 32-bit was affected
  as well.

It should be more robust now.
The changes on CellBuffer should be reviewed again, though.

* We can use the new SCI_SCROLLVERTICAL instead of SCI_SETFIRSTVISIBLELINE.
* The upgrade will also ease submitting the NetBSD-support patch.

* It requires a forced refresh on startup (even though that should be the
  default). Otherwise, it wouldn't print the info line correctly.
* Redirect stdin and pass it to newterm() to fix key queuing.
  Probably necessary for supporting ncurses on NetBSD as well.
* Avoid doupdate() if screen is too small: fixes crashes for very
  small windows.
* Updated Scintilla: There were some implicit typing assumptions,
  that are broken by this platform.

Unfortunately, it does not help with the slowdowns when editing files with very long lines.

* There are patches on top of Scintilla as were before
* Scinterm has been switched back to the upstream repository and there are unreleased
  commits - especially for out-of-tree builds.
* Lexilla hasn't been released since my troff lexer was merged.

* 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).