- couldn't get a functor on top of another working in GFSS2018, so now
we just copy the relevant definitions from ExtendFunctor and add the
Romance-specific ones
- add stare_V to DiffRomance (and essere_V for symmetry) so that we
can use it in ExtendRomance; using Latin verb name for fairness;
- add two missing lins to ExtendFunctor
+ related changes
