Merge branch 'ml/tcl86'

* ml/tcl86: git-gui: remove non-ttk code git-gui: remove ${NS} indirection for ttk git-gui: always use themed widgets from ttk git-gui: remove redundant check for Tk >= 8.5 git-gui: remove unreachable Tk 8.4 code git-gui: Make TclTk 8.6 the minimum, allow 8.7 Signed-off-by: Johannes Sixt <j6t@kdbg.org>