Use function table. Simplify logic

Size: 60364 -> 60220

functions.c

@@ -261,6 +261,7 @@ void FUNCTION_Select(FUNCTION_Type_t Function)
 		case FUNCTION_INCOMING:
 		case FUNCTION_RECEIVE:
 		case FUNCTION_BAND_SCOPE:
+		default:
 			break;
 	}