This includes 2 new methods wxVariant::IsValueKindOf() and
wxVariantData::GetValueClassInfo() to allow query of the
wxRTTI data of the variant's data.
Also included is a macro analogues to dynamicCast for fetching
objects out of a wxVariant.
Documentation patches for the above.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@20860 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775