Update for release 0.7.20

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@73347 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
bump file browser version number to 2.2

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@73348 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775