Add era package

[joeroe]

Adds era, a package providing classes and methods for formal representation of year-based timescales in R, such as the SI-based annus (ka, ma, etc.) system often used in palaeontology and the Before Present system often used in Quaternary palaeobiology and archaeology.

[willgearty]

Thanks for this suggestion @joeroe. I'm not entirely convinced this would be used much in deep-time paleontology, but I definitely see the usefulness for Quaternary work and archaeology. There is actually currently a proposal for a CTV for Archaeology (cran-task-views/ctv#64), and you should definitely look into making sure this gets included. However, given previous concerns about overlap between that potential CTV and this one, I would say we should probably avoid including era here in favor of including it there. If the Archaeology CTV doesn't work out, we could maybe look into adding a small Quaternary section to this task view.

[joeroe]

Thanks @willgearty. I'm a maintainer of the proposed archaeology CTV and era is already listed there.

Could you say a bit more a out why it isn't useful for palaeontology? Perhaps I can work on those areas.

[zeileis]

Thanks for the discussion. Just 2-3 quick comments from us as CRAN Task View Editors.

In cases where a certain package is clearly more geared towards task A rather than the related task B, then we recommend to only list the package in A. Then it should suffice to link the task views for A and B but one should try to avoid too many overlaps.

However, there are clearly packages for which listing in several task views is warranted because they are used frequently enough for both tasks, A and B.

Personally, I cannot judge which situation applies for the era package.

P.S.: We look forward to receiving an updated proposal for the ArchaelogicalScience task view 😁