TODO list:

General
 o Allow frox.conf to include other files.
 o Vary download speed depending on whether cache hit or miss.
 o Make MaxTransferRate controllable by CCPs.
 o Prevent repicking the same port for active connections to avoid occasional 
   TIME_WAIT problems ("425 Cannot open data connection")
 o Should bind_me() pick ports sequentially, not at random?

Possible
 o Virus scan uploads -- I'm not sure this is workable.
 o Socks support?
 o ? Move definition of sstr to header so sstr_len() can be an inline function.
 o Send server's 220 message as a commented 230
 o Listen on multiple IPs

Things I don't plan to do.

 o IPv6 for the moment.