Added partial keyword to core classes to make them easier to extend

Basic criterions:
- Class should be commonly accessed by users through the API
- or class describes the core structure of the framework
- or class is a key modifiaction point for custom extensions (GUI/Callbacks)
- and class is not containing only elements that are fetched in the whole assembly either way or is responsible for fetching additional content from assemblies

Adding an additional source file to the project with the same class heading will allow you to extend the partial classes with additional variables and functions, but not to change methods.
For that, you might need to extend and override classes if possible or directly modify the framework.

Node_Editor/Framework/DefaultNodeCalculator.cs

@@ -5,7 +5,7 @@
 
 namespace NodeEditorFramework
 {
-	public class DefaultNodeCalculator : INodeCalculator
+	public partial class DefaultNodeCalculator : INodeCalculator
 	{
 		// A list of Nodes from which calculation originates -> Call StartCalculation
 		public List<Node> workList;

Node_Editor/Framework/Node.cs

@@ -5,7 +5,7 @@
 
 namespace NodeEditorFramework
 {
-	public abstract class Node : ScriptableObject
+	public abstract partial class Node : ScriptableObject
 	{
 		public Rect rect = new Rect ();
 		internal Vector2 contentOffset = Vector2.zero;

Node_Editor/Framework/NodeCanvas.cs

@@ -5,7 +5,7 @@
 namespace NodeEditorFramework 
 {
 	[NodeCanvasType("Default")]
-	public class NodeCanvas : ScriptableObject 
+	public partial class NodeCanvas : ScriptableObject 
 	{ // Just contains the nodes and global canvas stuff; an associated NodeEditorState holds the actual state now
 		public virtual string canvasName { get { return "Calculation Canvas"; } }
 

Node_Editor/Framework/NodeCanvasSceneSave.cs

@@ -1,7 +1,7 @@
 using UnityEngine;
 using NodeEditorFramework;
 
-public class NodeCanvasSceneSave : MonoBehaviour 
+public partial class NodeCanvasSceneSave : MonoBehaviour 
 {
 	public string saveName;
 	public NodeCanvas savedNodeCanvas;

Node_Editor/Framework/NodeEditor.cs

@@ -14,7 +14,7 @@ namespace NodeEditorFramework
 	/// <summary>
 	/// Central class of NodeEditor providing the GUI to draw the Node Editor Canvas, bundling all other parts of the Framework
 	/// </summary>
-	public static class NodeEditor 
+	public static partial class NodeEditor 
 	{
 		public static INodeCalculator Calculator;
 

Node_Editor/Framework/NodeEditorCallbackReceiver.cs

@@ -6,7 +6,7 @@
 
 namespace NodeEditorFramework 
 {
-	public abstract class NodeEditorCallbackReceiver : MonoBehaviour
+	public abstract partial class NodeEditorCallbackReceiver : MonoBehaviour
 	{
 		// Editor
 		public virtual void OnEditorStartUp () {}
@@ -25,7 +25,7 @@ public virtual void OnAddConnection (NodeInput input) {}
 		public virtual void OnRemoveConnection (NodeInput input) {}
 	}
 
-	public static class NodeEditorCallbacks
+	public static partial class NodeEditorCallbacks
 	{
 		private static int receiverCount;
 		private static List<NodeEditorCallbackReceiver> callbackReceiver;

Node_Editor/Framework/NodeEditorGUI.cs

@@ -5,7 +5,7 @@
 
 namespace NodeEditorFramework 
 {
-	public static class NodeEditorGUI 
+	public static partial class NodeEditorGUI 
 	{
 		// static GUI settings, textures and styles
 		public static int knobSize = 16;

Node_Editor/Framework/NodeEditorSaveManager.cs

@@ -11,7 +11,7 @@ namespace NodeEditorFramework
 	/// <summary>
 	/// Manager handling all save and load operations on NodeCanvases and NodeEditorStates of the Node Editor, both as assets and in the scene
 	/// </summary>
-	public static class NodeEditorSaveManager 
+	public static partial class NodeEditorSaveManager 
 	{
 		#region Scene Saving
 

Node_Editor/Framework/NodeEditorState.cs

@@ -5,7 +5,7 @@
 
 namespace NodeEditorFramework 
 {
-	public class NodeEditorState : ScriptableObject 
+	public partial class NodeEditorState : ScriptableObject 
 	{ // holds the state of a NodeCanvas inside a NodeEditor
 		public NodeCanvas canvas;
 		public NodeEditorState parentEditor;

Node_Editor/Framework/NodeInput.cs

@@ -8,7 +8,7 @@ namespace NodeEditorFramework
 	/// <summary>
 	/// NodeInput accepts one connection to a NodeOutput by default
 	/// </summary>
-	public class NodeInput : NodeKnob
+	public partial class NodeInput : NodeKnob
 	{
 		// NodeKnob Members
 		protected override NodeSide defaultSide { get { return NodeSide.Left; } }

Node_Editor/Framework/NodeKnob.cs

@@ -15,7 +15,7 @@ public enum NodeSide { Left = 4, Top = 3, Right = 2, Bottom = 1 }
 	/// Abstract knob on the side of an node that handles positioning drawing with a texture and even labeling and positioning calls
 	/// </summary>
 	[System.Serializable]
-	public class NodeKnob : ScriptableObject
+	public partial class NodeKnob : ScriptableObject
 	{
 		// Main
 		public Node body;

Node_Editor/Framework/NodeOutput.cs

@@ -8,7 +8,7 @@ namespace NodeEditorFramework
 	/// <summary>
 	/// Node output accepts multiple connections to NodeInputs by default
 	/// </summary>
-	public class NodeOutput : NodeKnob
+	public partial class NodeOutput : NodeKnob
 	{
 		// NodeKnob Members
 		protected override NodeSide defaultSide { get { return NodeSide.Right; } }