Added support for querying large value tuples

[esentio]

It is now possible to return value tuples with 8 and more elements (where TRest is another value tuple).

It is supported in Query and QueryFirstOrDefault methods:

using (var db = CreateContext())
{
    var value = db.QueryFirstOrDefault<(int, int, int, int, int, int, int, int, int)>("SELECT 1, 2, 3, 4, 5, 6, 7, 8, 9");
    var list = db.Query<(int, int, int, int, int, int, int, int, int)>("SELECT 1, 2, 3, 4, 5, 6, 7, 8, 9");
}

And also in Select method:

Using db = CreateDbContext()
  Dim list = db.From(Of Article).
                Select(Function(x) (x.Id, x, 1, 2, 3, 4, 5, 6, 7, 8, 9)).
                ToList()
End Using

However, latter works only in VB.NET, since C# doesn't allow that currently.