Cleaned up code to remove duplicate blocks from multiple functions Added better handling of failed creation of wxDbTable/wxDb objects Moved code out of class constructors to a private function called from within the constructor Moved destructor code to a cleanup() function so it could be called from within the constructor if the constructor failed. Added wxDb::ModifyColumn() function. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@9255 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775