Add some xml documentation (#1643)

* add some xml doc

* add missing drag xml doc

* xml doc corrections

* more xml doc

Author: dga711

CefSharp/AddressChangedEventArgs.cs

@@ -14,6 +14,11 @@ public class AddressChangedEventArgs : EventArgs
         public IBrowser Browser { get; set; }
         public string Address { get; private set; }
 
+        /// <summary>
+        /// Called when a frame's address has changed. 
+        /// </summary>
+        /// <param name="browser">the browser object</param>
+        /// <param name="address">the address</param>
         public AddressChangedEventArgs(IBrowser browser, string address)
         {
             Browser = browser;

CefSharp/CEFCursorType.cs

@@ -4,6 +4,9 @@
 
 namespace CefSharp
 {
+    /// <summary>
+    /// Cursor type values.
+    /// </summary>
     public enum CefCursorType
     {
         Pointer = 0,

CefSharp/CefJsDialogType.cs

@@ -4,6 +4,9 @@
 
 namespace CefSharp
 {
+    /// <summary>
+    /// Supported JavaScript dialog types.
+    /// </summary>
     public enum CefJsDialogType
     {
         Alert = 0,

CefSharp/CefReturnValue.cs

@@ -4,6 +4,9 @@
 
 namespace CefSharp
 {
+    /// <summary>
+    /// Return value types.
+    /// </summary>
 	public enum CefReturnValue
 	{
 		/// <summary>

CefSharp/CefState.cs

@@ -4,6 +4,9 @@
 
 namespace CefSharp
 {
+    /// <summary>
+    /// Represents the state of a setting.
+    /// </summary>
     public enum CefState
     {
         /// <summary>

CefSharp/DefaultResourceHandlerFactory.cs

@@ -34,11 +34,22 @@ public virtual bool UnregisterHandler(string url)
             return Handlers.TryRemove(url, out handler);
         }
 
+        /// <summary>
+        /// Are there any <see cref="ResourceHandler"/>'s registered?
+        /// </summary>
         public bool HasHandlers
         { 
             get { return Handlers.Count > 0; }
         }
 
+        /// <summary>
+        /// Called before a resource is loaded. To specify a handler for the resource return a <see cref="ResourceHandler"/> object
+        /// </summary>
+        /// <param name="browserControl">The browser UI control</param>
+        /// <param name="browser">the browser object</param>
+        /// <param name="frame">the frame object</param>
+        /// <param name="request">the request object - cannot be modified in this callback</param>
+        /// <returns>To allow the resource to load normally return NULL otherwise return an instance of ResourceHandler with a valid stream</returns>
         public virtual IResourceHandler GetResourceHandler(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request)
         {
             try

CefSharp/DragOperationsMask.cs

@@ -7,6 +7,9 @@
 
 namespace CefSharp
 {
+    /// <summary>
+    /// "Verb" of a drag-and-drop operation as negotiated between the source and destination.
+    /// </summary>
     [Flags]
     public enum DragOperationsMask : uint
     {

CefSharp/DraggableRegion.cs

@@ -4,6 +4,9 @@
 
 namespace CefSharp
 {
+    /// <summary>
+    /// Representing a draggable region.
+    /// </summary>
     public struct DraggableRegion
     {
         public int Width { get; private set; }

CefSharp/ICookieVisitor.cs

@@ -4,6 +4,10 @@
 
 namespace CefSharp
 {
+    /// <summary>
+    /// Interface to implement for visiting cookie values. 
+    /// The methods of this class will always be called on the IO thread.
+    /// </summary>
     public interface ICookieVisitor
     {
         bool Visit(Cookie cookie, int count, int total, ref bool deleteCookie);

CefSharp/IDragData.cs

@@ -8,6 +8,9 @@
 
 namespace CefSharp
 {
+    /// <summary>
+    /// Used to represent drag data.
+    /// </summary>
     public interface IDragData : IDisposable
     {
         /// <summary>