Add enum overload to set the highlighter type

Author: gmarz

src/Nest/DSL/Search/HighlightFieldDescriptor.cs

@@ -138,6 +138,11 @@ public HighlightFieldDescriptor<T> Type(string type)
 			Self.Type = type;
 			return this;
 		}
+		public HighlightFieldDescriptor<T> Type(HighlighterType type)
+		{
+			Self.Type = type.GetStringValue();
+			return this;
+		}
 		public HighlightFieldDescriptor<T> PreTags(string preTags)
 		{
 			Self.PreTags = new[] { preTags };

src/Nest/Enums/HighlighterType.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.Serialization;
+using System.Text;
+
+namespace Nest
+{
+	public enum HighlighterType
+	{
+		[EnumMember(Value = "plain")]
+		Plain,
+		[EnumMember(Value = "postings")]
+		Postings,
+		[EnumMember(Value = "fvh")]
+		Fvh
+	}
+}

src/Nest/Nest.csproj

@@ -369,6 +369,7 @@
     <Compile Include="Enums\FieldDataLoading.cs" />
     <Compile Include="Enums\FieldDataNonStringFormat.cs" />
     <Compile Include="Enums\FieldDataStringFormat.cs" />
+    <Compile Include="Enums\HighlighterType.cs" />
     <Compile Include="Enums\NormsLoading.cs" />
     <Compile Include="Enums\RoutingAllocationEnableOption.cs" />
     <Compile Include="Enums\ScriptLang.cs" />

src/Tests/Nest.Tests.Unit/Search/Highlight/HighlightTests.cs

@@ -35,6 +35,7 @@ public void TestHighlight()
                         .NoMatchSize(200)
 						.PreTags("<em>")
 						.PostTags("</em>")
+						.Type(HighlighterType.Plain)
 					)
 				);
 			var json = TestElasticClient.Serialize(s);
@@ -54,7 +55,8 @@ public void TestHighlight()
 			  _all: {
 				pre_tags: [""<em>""],
 				post_tags: [""</em>""],
-				no_match_size: 200
+				no_match_size: 200,
+				type: ""plain""
 			  }
 			},
 			require_field_match: true,