Allow configuring many proxylists.

Now 64 separate chains are supported (easy to change).  A chain is selected using the PROXYCHAINS_CHAIN envvar.  I leave the default list as "ProxyList" for backwards compatibility, but I think it should really be default.  Chain names can be any string excluding the ']' character.  There are per chain timeout, chain type, and man_chain settings.  If these are no specified the global values will be used.

This is a step on the way to allowing chaining of proxy chains, the original goal.  The next step though will be tricky and I'm not even sure I have the semantics fully thought out.