Add support for wxICON_AUTH_NEEDED to wxMessageDialog.

Allow showing the standard "Authentication needed" dialog in the message boxes
under MSW.

Closes #15121.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73877 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Add empty paragraph in wxRichTextTable::AddColumns() and AddRows().

Do the same thing in Add{Columns,Rows}() as in CreateTable() to ensure the
proper cell creation.

Closes #15153,

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73878 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775