Add "Steps per hour" system setting

[szdarkhack]

This implements a "Steps per hour" system setting to be returned from PTM:GetStepHistory, as described in issue #208.

Currently the setting is global (i.e. not per-game).

[PabloMK7]

Can you send screenshot of the new UI? Also, would you be able to add the setting to android?

[szdarkhack]

The UI is shown below. I've tried my best to maintain the existing style and made sure it doesn't show in the per-game config.

I don't think I'll be able to do the Android UI, at least not for now, but I can try it when I get some spare time again. Also I tried to make the setting work per-game but failed, I certainly intend to take another crack at that at some point (if noone beats me to it).

Any suggestions for improving the setting label or any such detail are of course welcome. Maybe "Pedometer steps per hour" would be clearer?

[szdarkhack]

Terribly sorry, I just realized I had the wrong author set so I had to amend and force push.

[PabloMK7]

Please make sure to edit the non-qt citra so that it loads the setting from the .ini file. Also edit the Android files so that it does the same (even if no UI exists).
Take a look at the config.cpp changes in #209

[szdarkhack]

I've made the requested changes and tested that the ini value is properly loaded (and works as intended) for both the SDL frontend and the android version.