discord: retry auth/command register, do latter in bulk

re-use the auth retry options from the config for initial d.bot.Open and
for registering commands. The latetr is now done with the BulkOverwrite
    method, since it seems to work now. For #427.

main.go

@@ -542,7 +542,7 @@ func start(asDaemon, firstCall bool) {
 				discordEnabled = false
 			} else {
 				app.debug.Println(lm.InitDiscord)
-				go app.discord.run()
+				go app.discord.Run()
 				defer app.discord.Shutdown()
 				app.contactMethods = append(app.contactMethods, app.discord)
 			}