New in 0.21:
* Added support for emitting hyperlinks.
  New functions:
       TYPE                               FUNCTION
  styled_ostream_t          styled_ostream_set_hyperlink
  styled_ostream_t          styled_ostream_get_hyperlink_ref
  styled_ostream_t          styled_ostream_get_hyperlink_id
  term_ostream_t            term_ostream_set_hyperlink
  term_ostream_t            term_ostream_get_hyperlink_ref
  term_ostream_t            term_ostream_get_hyperlink_id
  html_ostream_t            html_ostream_set_hyperlink_ref
  html_ostream_t            html_ostream_get_hyperlink_ref
* The example programs support the NO_COLOR environment variable,
  as specified in https://no-color.org/.

New in 0.20:
* New class: noop_styled_ostream_t.
  New constructor function: noop_styled_ostream_create.

New in 0.8:
* Fixed a couple of reliability bugs:
  - When a program exits while the terminal was in non-default state, the
    library left the terminal with ECHO off.
  - The SIGCONT signal handler would fail to restore the proper styling,
    with a low probability.
  - The SIGTSTP and SIGCONT signal handlers could clobber errno.
* Added support for Windows consoles.
* Improved support for TERM=Eterm-256color and TERM=mlterm-256color.
* Added support for terminal emulators with true-color support (16 million
  colors), such as TERM=xterm-direct and TERM=konsole-direct.

New in 0.7:
* Reliable tty control, as described by the ttyctl_t enum, is now implemented.

New in 0.6:
* The ostream_t operation 'flush' now takes an additional argument, of type
  ostream_flush_scope_t.
* New functions:
       TYPE                               FUNCTION
  styled_ostream_t          styled_ostream_flush_to_current_style
  term_ostream_t            term_ostream_flush_to_current_style
  html_ostream_t            html_ostream_flush_to_current_style

New in 0.5:

* The libtextstyle library can now be built and installed independently
  of GNU gettext.
