Fix routing file and end tracking

Hi,

I spotted some behaviours that I believe are bugs on the master branch code and propose some fixes. Namely:

The loading/writing of routing GeoJSON file was inversing the order of the latitude/longitude data for sequential load/write of the same file (which was afterwards showing wrong paths on the map due to the reversed coordinates).The error was coming from the fact that the received/loaded data was reversed before usage but not reversed back to its original form. I added the reversing step in the file index.js. I also fixed accordingly the starting/ending routing trackers coordinates.
When ending a tracking, the app was continuing to track the user (i.e., marker kept in tracking mode and all the tracking metrics were still updated once a tracking was stopped). I tracked down the bug to the function 'measure_distance' in 'module.js' that was failing to execute properly the line
```
document.querySelector("tracking-speed-average-time").innerText = "";
```
which was inducing that the ending of the tracking procedure was not applied afterwards. I modified the line as follows
```
document.querySelector("div#tracking-speed-average-time").innerText = "";
```
and the app seems to work properly now.

Hope it helps.

strukturart / o.map