[Cleanup] Remove deprecated typedefs SubDomainIndexType and SubDomainType
[IndexSet] Implement new types() method

The old code somehow compiles (maybe dune-grid had a default
implementation of types()?), but segfaulted. Fixed now.

Kudos to Christoph Grüninger for reporting the issue.
[GeometryType] Clean up some loops over GeometryTypes to use new types() method

Also switch to a much cleaner range-based for loop while we're at it...