Save a default label size in label settings

app/routes/labels.py

@@ -435,6 +435,9 @@ def settings():
         # checkbox here genuinely means unticked.
         SiteSetting.set('tape_rotate_default',
                         bool(request.form.get('tape_rotate_default')))
+        SiteSetting.set('tape_size_mode',
+                        request.form.get('tape_size_mode')
+                        or tape_printer.DEFAULT_SIZE_MODE)
         db.session.commit()
         flash('Label settings saved.', 'success')
         return redirect(url_for('labels.settings'))
@@ -457,4 +460,7 @@ def settings():
         tape_printer_format=SiteSetting.get('tape_printer_format', '') or '',
         tape_default=SiteSetting.get('tape_default', tape_printer.DEFAULT_TAPE),
         tape_rotate_default=SiteSetting.get_bool('tape_rotate_default', True),
+        size_modes=tape_printer.SIZE_MODES,
+        tape_size_mode=SiteSetting.get('tape_size_mode',
+                                       tape_printer.DEFAULT_SIZE_MODE),
     )