default boolean shouldPropagate(@Nullable IPropagationPart to, int mode) {
        return true;
    }
Should be called by above forward/backwards methods as a final check to see if propagation
should continue to the given part.
@param to Part to propagate to
@param mode Propagation mode
@return True if propagation should continue
core/src/main/java/mrtjp/projectred/core/part/IPropagationHooks.java