Add start of selection api, support for HasSelection, SelectAll and DeleteSelection along with documentation. Implement for IE and WebKitGTK and add stubs for OSX WebKit.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/SOC2011_WEBVIEW@68195 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/osx/webview_webkit.h

@@ -99,8 +99,13 @@ public:
     virtual void Paste();
     
     //Editing functions
-    void  SetEditable(bool enable = true);
-    bool  IsEditable();
+    virtual void SetEditable(bool enable = true);
+    virtual bool IsEditable();
+    
+    //Selection
+    virtual void DeleteSelection();
+    virtual bool HasSelection() { return false };
+    virtual void SelectAll() {};
 
     // ---- methods not from the parent (common) interface
     wxString GetSelectedText();