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/webview.h

@@ -284,6 +284,10 @@ public:
     virtual void SetEditable(bool enable = true) = 0;
     virtual bool IsEditable() = 0;
 
+    virtual void SelectAll() = 0;
+    virtual bool HasSelection() = 0;
+    virtual void DeleteSelection() = 0;
+
     // TODO:
     //     wxString GetSelection();                         // maybe?
     //     void SetSelection(...);                          // maybe?