config: add support for "list" type

"list" is a list of strings, represented in the .ini as repeated entries
for a field, e.g.
url = myurl1
url = myurl2
Shown in the UI as multiple inputs with delete buttons.

main.go

@@ -232,7 +232,7 @@ func start(asDaemon, firstCall bool) {
 			app.err.Fatalf(lm.FailedCopyConfig, app.configPath, err)
 		}
 		app.info.Printf(lm.CopyConfig, app.configPath)
-		tempConfig, _ := ini.Load(app.configPath)
+		tempConfig, _ := ini.ShadowLoad(app.configPath)
 		tempConfig.Section("").Key("first_run").SetValue("true")
 		tempConfig.SaveTo(app.configPath)
 	}