rc-6-1-90
* configure.ac (AC_INIT): Set version to 6.1.90. (OCTAVE_PATCH_VERSION): Set to 90. (OCTAVE_COPYRIGHT): Update to 2021. (OCTAVE_RELEASE_DATE): Update to 2021-02-10. * liboctave/module.mk, libgui/module.mk, libinterp/module.mk: Bump version number for library revision.