Clamp extruder_count

- Issue MatterHackers/MCCentral#2616
Add extruder count constraints

SlicerConfiguration/SliceSettingsWidget.cs

@@ -469,7 +469,16 @@ namespace MatterHackers.MatterControl.SlicerConfiguration
 				switch (settingData.DataEditType)
 				{
 					case SliceSettingData.DataEditTypes.INT:
-						uiField = new IntField();
+
+						var intField = new IntField();
+						uiField = intField;
+
+						if (settingData.SlicerConfigName == "extruder_count")
+						{
+							intField.MaxValue = 4;
+							intField.MinValue = 0;
+						}
+
 						break;
 
 					case SliceSettingData.DataEditTypes.DOUBLE:

SlicerConfiguration/UIFields/IntField.cs

@@ -1,5 +1,5 @@
 /*
-Copyright (c) 2017, Lars Brubaker, John Lewin
+Copyright (c) 2018, Lars Brubaker, John Lewin
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
@@ -27,6 +27,7 @@ of the authors and should not be interpreted as representing official policies,
 either expressed or implied, of the FreeBSD Project.
 */
 
+using System;
 
 namespace MatterHackers.MatterControl.SlicerConfiguration
 {
@@ -34,10 +35,17 @@ namespace MatterHackers.MatterControl.SlicerConfiguration
 	{
 		private int intValue;
 
+		public int MinValue { get; set; } = int.MinValue;
+
+		public int MaxValue { get; set; } = int.MaxValue;
+
 		protected override string ConvertValue(string newValue)
 		{
 			decimal.TryParse(newValue, out decimal currentValue);
-			intValue = (int)currentValue;
+
+			// Clamp to range
+			intValue = Math.Min((int)currentValue, this.MaxValue);
+			intValue = Math.Max(intValue, this.MinValue);
 
 			return intValue.ToString();
 		}

Submodules/agg-sharp

@@ -1 +1 @@
-Subproject commit 62ffc915f217c8a2232810fb4f567f9b4b1009f3
+Subproject commit e28826c49a73ed885dd459b4631f021d6d26406c