* 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.

* This requires the new SCI_SETTABDRAWMODE(SCTD_CONTROLCHAR).
* It makes no sense to let TAB indent in TECO code as it can be
  the insert-with-tab command (^I).
  On the other hand large `I`-blocks could include TABs which are
  actually meant as indentations.

Hard tabs would even cause YAML syntax errors.

* Improves DEC TECO-11 compatibility.
* <EM> is still supported as a synonym, but considered deprecated and is no longer documented.
  A warning is printed when invoked.
  It can be repurposed at any time in the future.
* `EI$` is not yet supported.
  I am unsure whether this makes any sense.

Also, unterminated strings are highlighted with the "error" color now.

* grosciteco was just hardcoding "Monospace", regardless of what was configured via lexer.font in ~/.teco_ini
* The variable-width font used for ordinary "womanpage" body texts was hardcoded to "Serif".
  It is now configurable via the lexer.woman.font register.
* There is a difference, though:
  lexer.font has no default value and must therefore be checked everywhere.
  This is so you can set it even before munging lexer.tes.
  lexer.woman.font however has a default (Serif), so it can only be overridden after
  munging lexer.tes.
  Perhaps it would be easier and more consistent to have a default for lexer.font as well.