TODO list:

 o ? Use/write a string handling library for safer buffer overflow
   protection.
 o Rationalise use of iread, iwrite etc. now we no longer use signals.
 o Purge "Feature:" lines we don't support from end of greeting.
 o Resource Limits
 o Command line options for some config file stuff.
 o Allow running from inetd.
 o Allow passive-->active conversion. Is this useful? (N.B. 
   active-->passive conversion is already there).
 o Try and deal with caching of mirrored ftp hosts properly.
 o ? Autogenerate config file code from template.
 o Distinguish between hosts on the local net and those outside. 
   Useful for either security, or for letting PORT commands to outside
   hosts go through unchanged for FXP transfers.

Things I don't plan to do.

 o IPv6 for the moment -- I know little about it.
