This is a facade for wxDataViewCtrl allowing to easily work with multi-column
trees, possibly with an optional checkbox in the first column. Its API is very
similar to wxTreeListCtrl and it provides a simple migration path from the
latter.
Add the class itself, documentation for it and minimal unit tests.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@68916 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
