+ Navigator permission changes
» Changes the permission needed to open the navigator to buildsystem.navigator
» Adds a permission which is needed to receive the navigator item: buildsystem.navigator.item

+ Fixed bugs with the modern navigator
» Item used to close navigator could be dropped
» Players were able to modify other player's navigator leaving them unusable

+ Minor optimisation
» Reset unload task after world switch (or quitting) to ensure correct unload time