map L_TRIG to alt button

- switches immediately when releases L
- or whenevever L+Z is pressed. Will switch back when L is released.

src/include/types.h

@@ -2816,6 +2816,7 @@ struct player {
 	/*0x1c64*/ s32 unk1c64;
 	/*0x1c68*/ u32 unk1c68;
 	/*0x1c6c*/ u32 unk1c6c;
+	s16 altdowntime; // for alt-modes, used like invdowntime and amdowntime
 };
 
 struct ailist {