Standardize and shorten the lenght of coordinates

[kghbln]

This is an issue reported on mw.o which I think will be a nice enhancement:

I 'm wondering why the coordinates are so long: 14 numbers for latitude/longitude while only 6 would be enough for precision (cf. older version of Google Maps extension). As a result, when you draw long lines or add many points, the size of the page becomes too heavy.

Would it be possible to shorten them?

For instance: 47.254301,-1.679535 instead of 47.25430126476208,-1.67953552941873

[JeroenDeDauw]

it's about the coordinates created by the editor for a new map or when an old map is modified.

[kghbln]

Another advantage I see is that you will have much fewer coordinates code when doing polygons etc.