Various wxCollapsiblePane enhancements (re-patch 1577412):

1. wxUSE_COLLPANE added
2. XRC handler added
3. flicker fixes for the generic version
4. sizing fixes for GTK+ version
5. RTL fixes for the generic version (via wxBoxSizer)
6. better appearance under Mac for the generic version


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@42759 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/xrc/xh_all.h

@@ -66,5 +66,6 @@
 #include "wx/xrc/xh_hyperlink.h"
 #include "wx/xrc/xh_bmpcbox.h"
 #include "wx/xrc/xh_animatctrl.h"
+#include "wx/xrc/xh_collpane.h"
 
 #endif // _WX_XH_ALL_H_