* This is still rendered as underlined text.
* It uses a new Scinterm upstream feature, so we can
  switch back to the upstream repo.

It does not change anything functionally, though.

The new wcwidth.c wasn't actually linked in.

This requires enhanced INDIC_STRAIGHTBOX semantics, which are not yet upstream in Scinterm.

* This currently needs a yet unmerged patch, fixing the light colors.
* Scinterm no longer systematically initializes the color pairs, so
  we cannot predict their numbers - instead we initialize color pairs
  on demand and store them in a hash map, very similar to what Scinterm
  does internally.
* Scinterm v5.5 can use arbitrary RGB colors now by automatically
  allocating curses colors and pairs.
  We do not expose this in SciTECO yet, although that would also
  be possible.
  It has to be decided first whether the special predefined colors
  will continue to live in the same namespace along with "true"
  RGB colors.

* SCI_COLOR_PAIR() is now a function teco_color_pair() since it also became
  an inline function in Scinterm.

* If the background color would be non-black, render text in reverse
  video. ncurses doesn't do that automatically.
* Fixes rendering under historical terminals like VT100 and VT240,
  but also all of the monochrome versions of modern emulators in terminfo.
* This also improves the situation when $TERM is set to something conservative,
  e.g. when connecting via RS232.
* Scinterm is temporarily changed to my own fork, which already contains
  a monochrome patch.

* see https://github.com/orbitalquark/scinterm/issues/26
* scintilla_wnoutrefresh() actually caused a refresh(), thus updating the physical screen
  before calling teco_curses_info_popup_noutrefresh() and doupdate().
* This was visible when redrawing the both Scintilla view and popup often as happens during
  scrolling or when clicking on the popup borders.
* This was probably broken since v2.1.0.