Merge branch 'fix/use-auto-id-set-type' into 'master'

Fix/use auto id set type

Ids are not generally convertible to int. This fails
e.g. for yasp grids that uses Dune::bigunsignedint.
Further remark: Incrementing an Id might not always be possible.
Ids are also not guaranteed to be contiguous.
We should think about another method here!

See merge request !117