Write documentation for SOCKS5 proxy config.

Document the new SOCKS5 Proxy feature. References:

• https://wiki.secondlife.com/wiki/User:Log_Linden/Socks5Viewer
• https://wiki.secondlife.com/wiki/User:Log_Linden/Socks5Viewer/TestPlan

This requires updating existing docs on firewall / networking. There are too many of these and they need to be consolidated anyway:

• Configuring your corporate firewall to allow access to Second Life (Merged with "Configuring your firewall")
• Configuring your firewall
• Second Life IP addresses firewall configuration (Merged with "Configuring your firewall")
• How do I configure my software firewall (such as Norton Internet Security, McAfee Personal Firewall, or ZoneAlarm)? (Renamed to "Configure your software firewall")
• Is my firewall responsible for problems with Second Life? (Merged with "Configure your software firewall")
• Unusually restrictive firewalls block teleporting (Removed. "Solution" is covered by standard required ports listed in "Configuring your firewall")

Also, need to update Viewer Help as follows:

• Add "proxysettings" help ID to map file for "Second Life Developer/3.0.1.0" and subsequent versions.
• Write new Viewer Help UI reference article for the new floater.