Speed Scaling

[ursi]

This is an incomplete PR that adds support for adding a scaling factor to your wheel speed. I did this a few months back and I personally use it, but it's not complete in at least the following ways:

• only English translations
• trip distance should be scaled by the same factor as well
• I am not a kotlin/java/android dev so there could be simple mistakes

I really like this feature, but at least at the moment, I'm not gonna be bringing it home. I'm posting this PR to give it some visibility and on the off chance someone else may want to complete it, or use it in its current form.