Keyboard Tab Navigation

[jmillerv]

Implement tabbed navigation through the questions and saving/clearing buttons.

[jmillerv]

After doing some research it seems like the easiest way to get what I want is to refactor the app to use the new form code and pass in a struct w/ form data. Then take the struct and save it w/ a key to the preferences.

Going to require refactoring home.go, hopefully it reduces the code.

	formStruct := struct {
		Name, Email string
		Subscribe   bool
	}{}

	formData := binding.BindStruct(&formStruct)
	form := newFormWithData(formData)
	form.OnSubmit = func() {
		fmt.Println("Struct:\n", formStruct)
	}

func newFormWithData(data binding.DataMap) *widget.Form {
	keys := data.Keys()
	items := make([]*widget.FormItem, len(keys))
	for i, k := range keys {
		data, err := data.GetItem(k)
		if err != nil {
			items[i] = widget.NewFormItem(k, widget.NewLabel(err.Error()))
		}
		items[i] = widget.NewFormItem(k, createBoundItem(data))
	}

	return widget.NewForm(items...)
}