* Scinterm was simply rendering them as black, thus effectively
  breaking the Linux and FreeBSD vts with terminal.tes.
* I was considering to render light black as white on 8-color terminals,
  so it's always readable.
  However, if you add in A_BOLD there is a good chance that the
  color will end up grey - at least it does in the virtual terminals (consoles).
* There is no need to use bright colors in the Scintilla view defaults.
  E.g. 0xFFFFF is "light white".
  However on 8-color terminals this will be rendered like white anyway.
  The new defaults are closer to what terminal.tes does.

Will rarely be of use in SciTECO, but it's part of the officially merged commit.

* 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.

This is for some minor cleanup.

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

* Also updated A_XXX attributes to WA_XXX, where the "new" wattr_set() APIs
  are used. This doesn't make a difference on ncurses and PDCurses, but the
  X/Open standard demands it.
* Allow color pairs up to 32767 instead of only up to 32766.
* We now always require Curses wide-character APIs due to Scinterm,
  which has to use mvwin_wch(). We were practically depending on wide-character
  support anyway, so this shouldn't really restrict portability.
* teco_curses_add_wc() has been simplified, now that we can rely on
  wide-char APIs. Perhaps it should be removed altogether?

* Instead of ORing COLOR_PAIR() into attributes, always pass separate `pair` arguments.
  Since they are `short` this allows for up to 32767 color pairs.
  Previously, we could only count on 256 color pairs (or 128 for SciTECO and Scinterm each).
* Analoguous changes have been made to Scinterm.
  See also https://github.com/orbitalquark/scinterm/pull/37
  Since it only correctly checks for overflows at the end of the color pair space, we allocate the second
  half of that space to Scinterm.
  It is now very unlikely to overflow the color pair space, though.
* This wasn't critical of course since even the 128 pairs would be unlikely to exhaust as long
  as we support only 16 ANSI colors.
  Scinterm however supports arbitrary RGB colors and we might want to do so soon as well.

This requires a (yet unmerged) Scinterm patch.

The submodule has been reverted to its upstream URL.