Storyboard view hierarchy can lead to squashed subviews

[friedbunny]

Setting your storyboard up with the map view at the base level of the hierarchy like this:

Leads to the attribution button and logo bug being squashed after the initial load — i.e., load the MBGL view controller, switch to a different view controller, come back to MBGL and this happens:

Work around is to place the map view within another view, remembering to reset to suggested constraints:

/cc @1ec5

[1ec5]

The logo (and attribution button) both have intrinsic width and height constraints that are removed whenever the MGLMapView moves to a new superview, as is the case when returning to the tab view containing the MGLMapView. The compass is unaffected because it has a container view whose constraints are removed.