Add the ability to limit changeset size

[tomhughes]

This aims to allow the bounding box of changesets to be limited. The basic technology is the same as #4319 with the maximum size ramping up over a period of time for new users.

The defaults allow new users to start with a limit equivalent to a square of 1.5 degrees on each side, and ramp up to the whole world over 28 days with it taking just over three days to start increasing and penalties being applied if the user is reported.

The limit is on the linear dimensions (width + length) not the area of the bounding box to avoid people doing X and Y movements in separate changesets which would then always have an area of zero.

[gravitystorm]

All looks good to me, thanks!

[notevenaperson]

I don't know if this is the right place to bring this up. How about changing the openstreetmap-site to use a heatmap instead a box? The kind of spread out changesets are only annoying because of how the main site shows recent changes.

This change feels like a instance of tagging for the renderer, but here you're changing policy. Don't you see what's happening?

[tomhughes]

That's not the reason for this change - the reason for this is to make vandalism harder.

[notevenaperson]

That's not the reason for this change - the reason for this is to make vandalism harder.

I often see experienced editors rioting in the comments of a changeset made by a beginner for having a box that is spanning continents. Rather than being a problem regarding what editors are allowed to do, it's a problem with the UI of the website. I suppose this change is justifiable to prevent a type of vandalism that is hard to undo, but it wouldn't be justifiable if it was for the purpose I initially thought it was for.