Added overload to type filter

Author: q42jaap

src/Nest.Tests.Unit/Search/Filter/ConditionLess/ConditionLessTests.cs

@@ -247,10 +247,8 @@ public void TermsTest()
 		public void TypeTest()
 		{
 			this.DoConditionlessFilter(f => f.Type(string.Empty));
-			this.DoConditionlessFilter(f => f.Type(null));
+			this.DoConditionlessFilter(f => f.Type((string)null));
 		}
 
-
-
 	}
 }

src/Nest/DSL/Filter/TypeFilter.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
+using Nest.Resolvers;
 using Newtonsoft.Json;
 
 namespace Nest
@@ -18,6 +19,6 @@ internal override bool IsConditionless
 		}
 
 		[JsonProperty(PropertyName = "value")]
-		public string Value { get; set;}
+		public TypeNameMarker Value { get; set; }
 	}
 }

src/Nest/DSL/FilterDescriptor.cs

@@ -549,6 +549,23 @@ public BaseFilter Type(string type)
 			this.TypeFilter = filter;
 			return new FilterDescriptor<T>() { TypeFilter = filter };
 		}
+
+		/// <summary>
+		/// Filters documents matching the provided document / mapping type. 
+		/// Note, this filter can work even when the _type field is not indexed 
+		/// (using the _uid field).
+		/// </summary>
+		public BaseFilter Type(Type type)
+		{
+			var filter = new TypeFilter { Value = type };
+			if (filter.IsConditionless)
+				return CreateConditionlessFilterDescriptor("filter", filter);
+
+			this.SetCacheAndName(filter);
+			this.TypeFilter = filter;
+			return new FilterDescriptor<T>() { TypeFilter = filter };
+		}
+
 		/// <summary>
 		/// A filter that matches on all documents.
 		/// </summary>