For the full log of gretl changes since January 2000, see
<@url="http://gretl.sourceforge.net/ChangeLog.html">.

2023-12-05 version 2023c
- New commands "gridplot" and "gpbuild" for constructing
  composite plots
- "gnuplot" command: implement new option syntax to support
  multiple "bands" in a single plot (but continue to support
  the old band syntax until further notice)
- "panel" command: support the --cluster option to produce
  a greater variety of robust standard errors, including two-
  way clustering; add an option to use the Driscoll-Kraay
  covariance estimator; and support the --no-df-corr option
- "tsls" command: if the --robust option is given, compute a
  robust variant of the Hausman test
- "scatters" command: expose its time-series functionality
  under the name command-name "tsplots"
- String-valued series: support returning such series from a
  user function, and loosen the restrictions on assignment to
  such series
- New usage of the '*' operator to augment a string via
  repetition, for example: string s = "abc" * 3
- New function asort() for sorting arrays of all types
- New function corresp() to determine the correspondence (if
  any) between two series or vectors
- New function rgbmix() to do mixing of colors via their R, G
  and B channels
- String functions strsub(), regsub(), substr(), tolower() and
  toupper(): generalize to support strings arrays and string-
  valued series as arguments, as well as individual strings
- New function strvsort(): recodes a string-valued series such
  that the numeric codes correspond to the alphabetical order
  of the string values, or in line with a reordering specified
  by the user
- Add documentation for the functions dec2bin() and bin2dec(),
  which were first defined in version 2022b
- kdensity() function: clarify its documentation
- halton() function: remove the limit of 40 on the number of
  sequences this function can generate
- Input of numeric constants: support hexadecimal notation
- $sysinfo accessor bundle: add CPU information
- Fix bug dating from 2022c: broken handling of the syntax
  listname.series when used in a function that is called from
  within a loop
- Fix bug: possibly incorrect results when applying a vector
  selection to a string variable
- Fix bug: possibly incomplete results when compacting daily
  data to weekly
- Fix bug: wrong alignment when appending dated weekly data
- Fix bug: invcdf() and critical() misbehaving for the chi-
  square distribution with a CDF argument of 1.0
- Fix bug: pdf() giving NA for Chi-square with argument 0
- Fix bug: possible duplicate entries in GUI function package
  listing
- Fix bug: markdown conversion not always working properly
- Fix bug: "kdplot" command not respecting the --output option
- Fix bug: pexpand() function not working as advertised
- GUI: Add means of stacking side-by-side time series into
  panel series via the "Dataset structure" wizard
- GUI: Add a color selection dialog under the Tools menu
- GUI: use "Apply" and "OK" buttons more consistently
- GUI: make more apparent the facility to sort series in the
  main window by clicking the headers
- GUI: add a menu item to install a local function package,
  under the "/File/Function packages" menu
- GUI: add Ctrl + mouse wheel as a means of changing text
  size in various windows
- GUI editor and gretl_edit: add Ctrl-L keystroke for going
  to a specifed line, improve the search/replace dialog and
  fix a problem with automatic indentation
- Windows and macOS packages: add a dark GTK theme
- R interaction via embeddedR: update mechanism for determining
  R_HOME
