This has been broken since v2.5.2.

* Instead of supporting only 16 predefined RGB placeholder
  values in Scintilla messages and styles, you can now use
  arbitrary RGB values and colors are allocated via the terminal
  on the fly.
  You no longer need to call 3EJ to change the default color
  palette.
* The placeholder RGB values are still available.
  Since you will usually want exact RGB values when using
  anything outside of the range of 16 default colors
  and the RGB placeholders will not always exactly correspond
  to their RGB value, you can now call `0,3EJ` to ignore
  the default palette and allocate all colors dynamically.
* Allows for more than 16 colors on the screen simultaneously.
  Also simplifies the solarized.tes color scheme.
  Since both Scinterm and SciTECO try not to touch the 16
  default colors, you also no longer have to deal with
  restoring the palette after program termination
  (which was never reliable anyway).
* Color schemes with non-default colors (solarized.tes)
  may now be broken on TERM=linux-16color (Linux VT)
  since Scinterm will get only 8 colors, but solarized.tes
  needs 16.

* 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.

* I.e. you can now log warnings and errors from SciTECO code as well.
* We do not need a version of ^A accepting code points, since this is
  supported by ^T already.

* This could have been in ring.c, but in the future we may want to script
  the behavior in case recovery files are detected.
* The warnings are currently written as user messages, which looks
  ugly in interactive mode.
  Once n^A is supported, we can write them as regular warnings, though (FIXME).

* This is a gimmick pseudo-game for driving a tank around your buffer.
* The tank is "animated" and crushes non-space characters it drives over.
* When shooting, it deletes characters that get hit.
* When escaping, the tank explodes and leaves a "crater" behind.

There is no way to catch errors in ^Q since :^Q is already taken
as a dot-to-line conversion. :^Q is an extension, so we might still
want to repurpose it.

When editing TECO source files with fnkeys.tes, you could get unexpected cursor jumps
since SCI_GETCOLUMN counts all control characters as single columns and would always expand
tabs, even if tabs are drawn like control codes.

This could have been changed in Scintilla itself, but Neil decided that
SCI_GETCOLUMN and SCI_FINDCOLUMN will not be changed.
See https://groups.google.com/g/scintilla-interest/c/aqxapyAcRiA

* For consistency with other lexers, like the C/C++ lexer.
* `^*`, `^/` and `^#` are also true operators and shouldn't be styled
  as regular commands.
  This required introducing a new operator style (3).

* color.target is yellow in terminal.tes which looks awful and it should be
  used sparingly.
  The largest part of text in any lexer should be in the default colors.
* bash.tes now discerns between double and single quote strings like most lexers.
* autodetect GNUmakefiles
* yaml.tes now uses color.string for keys - this is for consistency with JSON
  where keys will also always be strings.