Be able to calculate/record the zoom level of the map when a location is manually selected by a user

[ColinCampbell]

Be able to calculate/record the zoom level of the map when a user manually selects a location in a geopoint question.

We've found that some users of our surveys select locations manually from the map at zoom levels that aren't appropriate for what they're recording.  If we could record the map zoom level at the point they manually selected their location we could measure how often this was the case and exclude the records if necessary.

This would be especially useful for surveys aimed at the general public, where there may be large numbers of participants submitting data who may not appreciate the need for accurate locations.

An alternative/extension of this would be to limit the maximum zoom level of the map at which a location can be manually selected and/or be able to provide a warning for people to zoom closer in (in a similar manner to the GPS accuracy threshold settings).