Sort stops by proximity to current GPS location

[fcucino]

Since the bus stops' names are not so self-explanatory and easy to find (direction matters also), I think that having the ability to sort stops list by proximity to the current phone GPS location could help to find better the intended stop.

[Stypox]

This might be a good idea, however it requires location permission and keeping track of the current user location (e.g. waiting for it to load and updating it if the user moves), which isn't so simple to do. I will not implement it, though if someone wants to open a pull request they are welcome (in which case I'm open to questions) :-)