Add support for id ranges to XRC.

Allow to declare ranges of consecutive IDs in XRC by using the "id[n]" syntax.
Show this functionality in the xrc sample and test it in the new unit test.

Also show and test the "object reference" XRC functionality.

Closes #11431.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66059 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/xrc/xrcdemo.cpp

@@ -64,10 +64,11 @@ bool MyApp::OnInit()
         return false;
 
     // If there is any of a certain format of image in the xrcs, then first
-    // load a handler for that image type. This example uses XPMs, but if
-    // you want PNGs, then add a PNG handler, etc. See wxImage::AddHandler()
+    // load a handler for that image type. This example uses XPMs & a gif, but
+    // if you want PNGs, then add a PNG handler, etc. See wxImage::AddHandler()
     // documentation for the types of image handlers available.
     wxImage::AddHandler(new wxXPMHandler);
+    wxImage::AddHandler(new wxGIFHandler);
 
     // Initialize all the XRC handlers. Always required (unless you feel like
     // going through and initializing a handler of each control type you will