Implement LINQ operators for Id

[tpluscode]

It would be nice to allow complex filters on entity id, like namespace matches.

For one it should be possible to get a string representation of the Id

from person in context.AsQueryable<IPerson>()
where person.Id.ToString().StartsWith("http://example.com")
select person;

Although specialized extension methods could cover most common cases eg

from person in context.AsQueryable<IPerson>()
where person.Id.IsInNamespace("http://example.com")
select person;

or even by using prefix

from person in context.AsQueryable<IPerson>()
where person.Id.IsInNamespace("foaf")
select person;