Avoid redundant virtual screen updates

Remove some redundant wnoutrefresh() invocations. There's no need to
copy a window to the virtual screen unless doupdate() is invoked
immediately afterwards.

This reduces flicker when browsing in the calendar panel.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

src/custom.c

@@ -879,7 +879,6 @@ print_key_incolor (WINDOW *win, char *option, int pos_y, int pos_x)
   custom_apply_attr (win, color);
   mvwprintw (win, pos_y, pos_x, "%s ", option);
   custom_remove_attr (win, color);
-  wnoutrefresh (win);
 }
 
 static int