Fixing #1397 and some other stuff

In src/karts/kart_properties.cpp the indetation is fixed and tracks now have a default_number_of_laps-attribute. But I'm still wondering about the use of these lines from track_info_dialog.cpp:
```
if (UserConfigParams::m_artist_debug_mode)
    m_spinner->setMin(0);
```

I also created ad641ef by playing around a bit with sed (I finally used ```for I in `tree -i -f src | grep \\.[hc]pp`; do cat $I | sed '/\/\/ ==/ y/=/-/' > $I.new && mv $I.new $I; done```) and commiting accidentally; if you like it you can re-revert it. (and if not I learned about using sed ;))