Add wxTextCompleter class which allows to return the possible completions
dynamically and wxTextCompleter::AutoComplete() overload using it. So far this
is only implemented for wxMSW.
Also fix calling wxTextEntry::AutoComplete(wxArrayString) multiple times under
MSW, this didn't correctly update the list of shown completions before.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67511 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
