proxy ftp: instead of using the hardwired string "text/plain" as

a fallback type for files served by the ftp proxy, use the
ap_default_type() function to determine the configured type.
This allows for special configurations like
 <Directory proxy:ftp://some.host>
 DefaultType gargle/blurb
 </Directory>
Additionally, add the Content-Encoding: header to FTP proxy replies
when the encoding is defined (by the AddEncoding directive).
Because it was missing, it was almost impossible to browse compressed
files using the FTP proxy (works now perfectly in Communicator).


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@83030 13f79535-47bb-0310-9956-ffa450edef68