Managing subseries in biblatex, with number inside subseries.

I.e 

````
@book{xxx,
   series={Corpus Scriptorum Christianorum Orientalum},
   number={78},
   subseries={Scriptores Arabici},
   subnumber={12}
   }
````

Maïeul Rouquette - 2015… - LPPL 1.3

http://latex-project.org/lppl/lppl-1-3c.html

Feature requests and bug reports can be made in https://git.framasoft.org/maieul/biblatex-subseries/issues