The topic order. When we're about to show a list of open topics, we'll sort the list in ascending order of this property, then in ascending order of title. By default, we set this order value to 1000; if individual goals don't override this, then they'll simply be sorted lexically by topic name. This can be used if there's some basis other than alphabetical order for sorting the list.

Compare this goal to another, for the purposes of sorting a list of topics. Returns a positive number if this goal sorts after the other one, a negative number if this goal sorts before the other one, 0 if the relative order is arbitrary.

By default, we'll sort by topicOrder if the topicOrder values are different, otherwise alphabetically by title.