Fix SceneAccessTool build fail issue (#274)

* Added the Quick Scene Access Tool

* removed unused file

* orgainized script for SceneAccessTool to their proper folders. Build should work now

UOP1_Project/Assets/Scripts/SceneManagement/ScriptableObjects/SceneAccessHolderSO.cs

 using System;
 using System.Collections.Generic;
-using UnityEditor;
-public class ReadOnlyAttribute : PropertyAttribute
-{
-
-}
-
-[CustomPropertyDrawer(typeof(ReadOnlyAttribute))]
-public class ReadOnlyDrawer : PropertyDrawer
-{
-	public override float GetPropertyHeight(SerializedProperty property,
-											GUIContent label)
-	{
-		return EditorGUI.GetPropertyHeight(property, label, true);
-	}
-
-	public override void OnGUI(Rect position,
-							   SerializedProperty property,
-							   GUIContent label)
-	{
-		GUI.enabled = false;
-		EditorGUI.PropertyField(position, property, label, true);
-		GUI.enabled = true;
-	}
-}
 /// <summary>
 /// It holds a list of scenes that's shown in the scene quick access tool
 /// </summary>

UOP1_Project/Assets/Scripts/Attributes.meta

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+folderAsset: yes
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UOP1_Project/Assets/Scripts/Attributes/Editor.meta

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UOP1_Project/Assets/Scripts/Attributes/Editor/ReadOnlyDrawer.cs

+using UnityEngine;
+using UnityEditor;
+
+/// <summary>
+/// This class contain custom drawer for ReadOnly attribute.
+/// </summary>
+[CustomPropertyDrawer(typeof(ReadOnlyAttribute))]
+public class ReadOnlyDrawer : PropertyDrawer
+{
+	/// <summary>
+	/// Unity method for drawing GUI in Editor
+	/// </summary>
+	/// <param name="position">Position.</param>
+	/// <param name="property">Property.</param>
+	/// <param name="label">Label.</param>
+	public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
+	{
+		// Saving previous GUI enabled value
+		var previousGUIState = GUI.enabled;
+
+		// Disabling edit for property
+		GUI.enabled = false;
+
+		// Drawing Property
+		EditorGUI.PropertyField(position, property, label);
+
+		// Setting old GUI enabled value
+		GUI.enabled = previousGUIState;
+	}
+}

UOP1_Project/Assets/Scripts/Attributes/Editor/ReadOnlyDrawer.cs.meta

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UOP1_Project/Assets/Scripts/Attributes/ReadOnlyAttribute.cs

+using UnityEngine;
+
+/// <summary>
+/// Read Only attribute.
+/// Attribute is use only to mark ReadOnly properties.
+/// </summary>
+public class ReadOnlyAttribute : PropertyAttribute { }

UOP1_Project/Assets/Scripts/Attributes/ReadOnlyAttribute.cs.meta

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UOP1_Project/Assets/Scenes/Skybox/ClearSky.meta

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