ftp proxy: various cosmetic and functional improvements

 - Allow for /%2f hack (to access the root directory / )
 - properly escape generated links in dir listing
 - do directory listings in ASCII, to avoid problems with EBCDIC servers
 - close data & control channels to server properly
 - rename "BUFF f" to "BUFF data" or "BUFF ctrl", depending on its FTP use


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@93054 13f79535-47bb-0310-9956-ffa450edef68