prompt to save if closing form and changes have been made

SpriteLibrary/SpriteEntryForm.cs

@@ -370,9 +370,16 @@ namespace SpriteLibrary
         }
 
         private void SpriteEntryForm_FormClosing(object sender, FormClosingEventArgs e)
+        {
+            if (PromptToApplyChangesAndContinue())
             {
                 myDatabase.Save(); //try saving the file
             }
+            else
+            {
+                e.Cancel = true;
+            }
+        }
 
         private void pbImageField_MouseMove(object sender, MouseEventArgs e)
         {