Move Improve This Map to macOS SDK

[1ec5]

macosapp currently implements an Improve This Map item under the Help menu. This design is HIG-compliant, and it’s where users would expect to find this functionality. But developers shouldn’t have to reinvent this code in each application they write.

-[MapDocument giveFeedback:] should be implemented as an action on MGLMapView, so that developers can simply connect a menu item to the first responder’s -giveFeedback: action. Going a step further, maybe MGLMapView could append an Improve This Map item to the Help menu if one isn’t found. But that might be too aggressive and make too many assumptions about the host application, so let’s stick to just the action for now.

[1ec5]

Fixed in #5999 on the iOS SDK v3.4.0 / macOS SDK v0.3.0 release branch.