extend traccar avl module with speed (and heading?) info

[wkulesza]

Currently, traccar avl module passes on information about device, lat/lon, date stamp.

It would be handy, if it passed on also speed and heading - it is included in the api response in traccar api.

[wkulesza]

Now the traccar module passes that info, but there are differences:
traccar (and traccar api) say 60km/h, at the same time transitclock says 120km/h and when checking the gtfs-rt vehicle positions api in transitclock, it says speed: 35., so everything seems to be divided by two (the avl log also seems to display the same value as gtfs-rt vp produced by transitclock, so 35).

edit: 35 is in m/s, but this must be wrong as this bus can't be going 35m/s as this is 120km/h...