* terex disables assertions by default unless you add `-DREG_DEBUG`.
  Since we heavily modified the original by Henry Spencer it makes sense
  to enable assertions.
* dlmalloc will still be built without assertions even if --enable-debug
  is given since that has a significant speed impact and I consider
  dlmalloc to be rock solid. It would need `-DDEBUG=1` to enable assertions
  (among other things).
  We only disable additional checks in dlmalloc if --disable-debug.

* terex is based on Henry Spencer's regular expression engine for Tcl.
  It is a hybrid NFA/DFA design which has better worst-time runtimes than
  the backtracking PCRE. Memory usage is also limited and can no longer
  increase catastrophically.
* It should no longer be possible to crash SciTECO with pathological
  searches.
* Since it reliably supports partial matches (REG_EXPECT) we can
  now enable the new backwards-search algorithm by default.
  This used to be broken because of a glib bug, which I already
  fixed. It would however take a long time until this ends up
  on the majority of glib installations.
* Regexp executions can still be quite slow if you are looking
  for a pattern at the end of a huge file, which can hang the editor,
  but this can now at least theoretically be solved by adding
  hooks into terex to poll for interruptions.
* We can now also get rid of a TECO-pattern to regexp translation
  step by directly generating terex tokens (TODO).
* Performance-wise terex appears to be slower than PCRE for simple
  forward searches even when linking everything with optimzations (FIXME).
* Having a stand-alone regular expression engine is also a huge
  step in getting rid of glib.

See also: https://git.fmsbw.de/terex/about/

* Turns out that not all UNIXes support sbrk().
  FreeBSD arm64 and riscv ports don't implement sbrk().
  It's also apparently not in POSIX - so other systems might also
  be affected.
  This needs to be passed on to dlmalloc.
* We now use DLMALLOC_CPPFLAGS instead of conditionals to pass
  on flags to dlmalloc.
* Should be backported to the FreeBSD v2.5.2 package
  to fix Poudriere fallout.

* The terminal's default foreground and background colors
  are now used by default (`sciteco --no-profile`), so SciTECO
  integrates naturally into all terminal color schemes, even
  dark-on-bright ones.
* The default Scintilla colors use only 0x000000 (COLOR_BLACK) and 0xC0C0C0 (COLOR_WHITE)
  now.
* You can use `7EJ` to configure the default colors in color
  schemes or your profile.
  All existing color schemes had to disable default colors
  (`-1,-1,7EJ`) since they wouldn't look well otherwise.
* You may add `-1,7EJ` to ~/.teco_ini when using a terminal emulator
  with a washed-out palettized COLOR_BLACK.
  We cannot detect the terminal's default colors automatically.
* Scinterm updated to v6.0.
  We require a not-yet-upstreamed patch:
  https://github.com/orbitalquark/scinterm/pull/40
* In fact, we might decide not to support default colors at all in Scinterm,
  so this feature should be considered experimental.

* signal() sets SA_RESTART by default.
* Some syscalls can theoretically block indefinitely.
  Even opening a special file could result in an indefinitely
  blocking operation, that should be interruptible.
  You must still poll teco_interrupted in these read() loops of course.
* Also makes sure that clipboard operations are interruptible
  even if $SCITECO_CLIPBOARD_GET blocks.
  Although I couldn't provoke problems in practice,
  I did observe hangs with xclip on Wayland on Linux,
  that could only be resolved by manually killing xclip.

* Hopefully also fixed FreeBSD CI builds. Always define NCURSES_WIDECHAR.
* Windows builds were probably also broken.
  We now pass down PDC_WIDE and PDC_FORCE_UTF8 into Scinterm as well.

Also, Scinterm had to be updated again since NetBSD curses stores up to 8 wchar_t per cell.

* We fork after command line arguments have been parsed, which
  is after gtk_get_option_group() has been called.
  This means that GTK was already initialized and it wasn't safe
  to continue after forking.
* As a workaround, we now re-exec with the original argv array,
  so GTK can be properly reinitialized.
  Since we did not remove `--detach` from argv (and that would be
  nontrivial), it would fork again endlessly,
  so we use an environment variable
  $__SCITECO_DETACHED to guard against recursive forks.
* Also, do not close stdin/stdout/stderr if has been redirected
  to a file, so you can now e.g. call `gsciteco -d >some-file`.
* This was broken since v2.5.0.