Add a crosshair size option

5 sizes are available (from 0 to 4), with 2 being the default vanilla-like
value.

Size 0 is a dot with alpha adjusted to match the crosshair color
settings.

src/include/types.h

@@ -6155,6 +6155,7 @@ struct extplayerconfig {
 	f32 crosshairsway;
 	s32 extcontrols;
 	u32 crosshaircolour;
+	u32 crosshairsize;
 };
 
 #endif