Keep the battery display when paused from the console (issue #56)

draw_cal_status() clears the whole left panel, the battery included. The
battery is redrawn when a sweep completes, which does not happen while
paused, so after the "pause" command (it draws the status panel directly)
the battery and voltage stayed blank. draw_cal_status() now also requests
the battery redraw (not in output mode, which shows no battery).

Tested on a ZS407 and a tinySA BASIC: battery and voltage shown after
"pause". +8 B.

ui.c

@@ -6495,6 +6495,7 @@ redraw_cal_status:
 #endif
     return;
   }
+  redraw_request |= REDRAW_BATTERY;    // the fill erased it, while paused no completed sweep redraws it
 
     //  if (current_menu_is_form() && !in_selftest)
 //    return;