Edit Auto iterate through configuration inputs with toggle

This is a new PR since there was some issues with git and my last one. This is just an extension of https://github.com/dolphin-emu/dolphin/pull/493

I have now  added a new option for toggling the the iteration.

I  created this since there was various concerns with the way the user would use the iterate feature, I feel like this clears them up.
Class variables should be prefixed with `m_`