fix: Fixed compilation errors in Usage Examples and applied a few minor fixes to them

Author: SolidAlloy

Editor/Drawers/TypeReferencePropertyDrawer.cs

@@ -11,8 +11,7 @@ namespace TypeReferences.Editor.Drawers
     /// </summary>
     /// <remarks>The class is public because it is used in the Samples package.</remarks>
     [CustomPropertyDrawer(typeof(TypeReference))]
-    [CustomPropertyDrawer(typeof(TypeOptionsAttribute), true)]
-    internal class TypeReferencePropertyDrawer : PropertyDrawer
+    public class TypeReferencePropertyDrawer : PropertyDrawer
     {
         public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
         {

Samples~/Usage Examples.meta

@@ -1,8 +1,7 @@
 namespace TypeReferences.Demo.Editor
 {
-    using System;
     using System.Reflection;
-    using SolidUtilities.Editor.Extensions;
+    using SolidUtilities.UnityEditorInternals;
     using TypeReferences.Editor.Drawers;
     using UnityEditor;
     using UnityEngine;
@@ -33,14 +32,14 @@ public void Draw()
 
         private void SetInheritsAttributeIfFound(MemberInfo field)
         {
-            var inheritsAttribute = (InheritsAttribute) Attribute.GetCustomAttribute(field, typeof(InheritsAttribute));
+            var inheritsAttribute = field.GetCustomAttribute<InheritsAttribute>();
             if (inheritsAttribute != null)
                 _fieldDrawer.SetAttribute(inheritsAttribute);
         }
 
         private void SetTypeOptionsAttributeIfFound(MemberInfo field)
         {
-            var typeOptionsAttribute = (TypeOptionsAttribute) Attribute.GetCustomAttribute(field, typeof(TypeOptionsAttribute));
+            var typeOptionsAttribute = field.GetCustomAttribute<TypeOptionsAttribute>();
             if (typeOptionsAttribute != null)
                 _fieldDrawer.SetAttribute(typeOptionsAttribute);
         }

Samples~/Usage Examples/Editor/TypeReferenceField.cs

@@ -1,5 +1,6 @@
 namespace TypeReferences.Demo.Look_Customization
 {
+    using UnityEngine;
     using Utils;
 
     public class GroupingModes : TypeReferenceExample
@@ -15,6 +16,7 @@ public class GroupingModes : TypeReferenceExample
 
         [InfoBox("Finally, types can be grouped in the same way as Unity does for its component menu. This " +
                  "grouping method must only be used for MonoBehaviour types. Enable it with Grouping.ByAddComponentMenu.")]
-        [TypeOptions(Grouping = Grouping.ByAddComponentMenu)] public TypeReference LikeAddComponent;
+        [Inherits(typeof(MonoBehaviour), Grouping = Grouping.ByAddComponentMenu)]
+        public TypeReference LikeAddComponent;
     }
 }

Samples~/Usage Examples/Look Customization/GroupingModes.cs

@@ -5,7 +5,7 @@
     public class IncludeAdditionalAssemblies : TypeReferenceExample
     {
         [InfoBox("By default, only the types the class can reference directly are included in the drop-down " +
-                 "list. In this example, CustomAssembly only has access to the TypeReferences assembly.")]
+                 "list. In this example, CustomAssembly only has access to the System and TypeReferences assemblies.")]
         public NoAttributeStruct NoAttribute;
 
         [InfoBox("But when we use [TypeOptions(IncludeAdditionalAssemblies = new []{ \"Assembly-CSharp\" })], " +