SnLinq support for the Client.NET

[kavics]

Create a LINQ provider for the Client.NET. Example code:

1. Get a user by part of loginname

   var user = repository.Content.All
   .OfType<User>()
   .Where(u => u.LoginName.Contains("john"))
   .FirstOrDefault();

2. Get the latest 5 articles

   var articles = repository.Content.All
   .OfType<Article>()
   .Where(a=> a.InTree("/Root/Content/Articles"))
   .OrderByDescending(a => a.CreationDate)
   .Take(5)
   .ToArray();