[Therion] How to get the right count for cave lengths

[Tarquin Wilton-Jones]

> Maybe a new statistics option is desirable;
> 
> *statistics <surface-length on/off>*, with the default [off] matching
> the current behaviour


Or a new value for topo-length, such as:
statistics topo-length all
But yes, your suggestion covers a few other cases, such as making sure
it is also included in carto statistics, which is also nice, imho.

It is filed here, but without any suggestion for how to implement it -
feel free to add your comment to it, with your suggested option name:
https://github.com/therion/therion/issues/132

Your idea of being able to show/sort by carto-length is also great. Not
that it matters to our project right now, since I am the only one
currently drawing up, but if someone else draws up a single scrap, it
would be a little disproportionate to show them first just because their
name sorts higher.

Copyright, though, is a legal state, so it doesn't really matter so much
to me about the ordering - (though yes, I can see why you might want
it). Its main need for being there is to say to people "you need to
contact these organisations for permission". But I did notice that it
only pulls the copyright information from the scraps, not from the
centreline, which means that if club A does the surveying (and therefore
holds copyright of the data), and club B does the cartography, it will
only show club B as copyright holders of the survey. In such a case, the
drawn survey is a derived work of the data, and therefore anyone who
needs to seek permission to make a derived work would need to seek
permission from both club A and club B.