convert extension: Add support for username mapping Allows mapping usernames to new ones during conversion process. - Use -A option for first import - Then at the end of the conversion process and if the destination repo supports authorfile attribute, author map content is copied to the file pointed by the authorfile call. - On incremental conversions w/o any -A option specified, the destination authorfile, if any, gets read automatically. EG: This allows mapping unix system usernames used in CVS accounts to a more typical "Firstname Lastname <address@server.org>" pair.