Add vocal warning about speeding

[Michal-Szczepaniak]

Please :)

[rinigus]

That could become seriously annoying without proper settings or insufficient data on the current road segment. Would have to think about it.

[Izaic]

I like the idea, but having it be configurable would be important. For example being able to set a custom figure for how much over before it starts giving a auditory warning. Otherwise it'd start yelling the second you go 1 MPH over.