Use double-nick in whois on query to get idle time

This queries server of the other user and not current user, which does
not know idle time.
See http://superuser.com/a/272069/208074.

Override is done before command is being sent to the server: if a
single argument is given to `/whois`, it is being repeated, otherwise
the command is sent as is.

src/client.js

@@ -52,6 +52,7 @@ var inputs = [
 	"raw",
 	"topic",
 	"list",
+	"whois"
 ].reduce(function(plugins, name) {
 	var path = "./plugins/inputs/" + name;
 	var plugin = require(path);

src/plugins/inputs/whois.js

@@ -0,0 +1,15 @@
+"use strict";
+
+exports.commands = ["whois"];
+
+exports.input = function(network, chan, cmd, args) {
+	if (args.length === 1) {
+		// This queries server of the other user and not of the current user, which
+		// does not know idle time.
+		// See http://superuser.com/a/272069/208074.
+		network.irc.raw("WHOIS", args[0], args[0]);
+	} else {
+		// Re-assembling the command parsed in client.js
+		network.irc.raw(`${cmd} ${args.join(" ")}`);
+	}
+};