Refine geolocation params to (try to) avoid bugs

[bbecquet]

Description

Pass an explicit maximumAge parameter to the getCurrentPosition call made in direction form, to allow the browser to reuse a "recent" position if it currently has one in cache.
(Also use enableHighAccuracy, which seems relevant for the directions.)

Why

Chromium/Webkit-based browsers seem to have issues with the geolocation.
https://bugs.chromium.org/p/chromium/issues/detail?id=586015
The default maximumAge is 0, in theory forcing getCurrentPosition to request a fresh position each time, but apparently this process may fail if a watchPosition is running and hasn't updated the position recently (hinting about another level of internal cache mechanism…).
By using an explicit maximumAge value, the browser is allowed to re-use immediately a previous position without requesting a new one, reducing the number of cases when it will fail.
The 5 minutes value is a trade-off, it should match a majority of use cases of the app while ignoring really too old positions…

[amatissart]

It looks good to me after some tests on Linux and Android, for both Chrome and Firefox.

In some cases, I observed a geolocation timeout after repeated selections of "Your position" in the direction inputs, specifically on Firefox on my laptop. But that's not a new problem (already observed after #886), and I cannot find any reproducible pattern for this.