The submodule has been reverted to its upstream URL.

See also https://github.com/orbitalquark/scinterm/pull/35

* 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.