spectrum analyzer assignable to Side button, close #478

Signed-off-by: Krzysiek Egzmont <egzumer@gmail.com>

ui/menu.c

@@ -362,6 +362,9 @@ const t_sidefunction gSubMenu_SIDEFUNCTIONS[] =
 #ifdef ENABLE_BLMIN_TMP_OFF
 	{"BLMIN\nTMP OFF",  ACTION_OPT_BLMIN_TMP_OFF}, 		//BackLight Minimum Temporay OFF
 #endif
+#ifdef ENABLE_SPECTRUM
+	{"SPECTRUM",         ACTION_OPT_SPECTRUM}
+#endif
 };
 
 const uint8_t gSubMenu_SIDEFUNCTIONS_size = ARRAY_SIZE(gSubMenu_SIDEFUNCTIONS);