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

2021-09-30 version 2021d
- "biprobit" command: include rho in $coeff, $stderr and
  $vcv
- New function lpsolve(): supports linear programming via
  the lpsolve library
- Prevent opening of general and console preferences
  dialogs simultaneously
- Fix partial breakage of the panel-time plotting facility
- Fix potential failure mode in echoing script input lines
  in the GUI program
- Fix a small and somewhat unlikely memory leak
- Fix a GUI build error when using GTK 2
- Fix Windows bug: greek-letter identifiers not working
  in some locales
- Fix Mac bug: binary data read/write not accessible
- Fix Linux bug: possible crash when running MPI from the
  GUI program
