Allow hostname in "Source port" field in SSH tunnel configuration

[vovcacik]

Hi,
putty lets you specify an IP address in "Source port" input field on "Tunnels" configuration tab, but I would really like if I could specify a hostname instead.

Example:

• instead of Source port: "127.0.0.99:8080" -> Destination: "localhost:8080"
• something like Source port: "apache99:8080" -> Destination: "localhost:8080"
• apache99 is alias for 127.0.0.99

Managing tunnels like this has some nice features. Hosts file (in case of Windows) is single source of truth when it comes to translating service aliases to IPs. Assigning remote server a unique local IP address (127.0.0.99) lets you work with the remote services transparently (no port reassign, browsers don't mix up saved passwords together etc.).