Added some nullability qualifiers in method implementation selectors for consistency with declarations.
The user dot view now has a non-zero size. Previously only its layer was sized properly. Also resolved some pedantic warnings about missing designated initializer overrides.
Xcode 6.3 or above is now required for building this project.
`Map` should be able to deal with having no access token or JSON even while it’s running. Most of `Map` accounts for this situation, but `reloadStyle()` incorrectly assumes that one or the other is set. This change corrects the assumption in `reloadStyle()`.
Also expose the access token and style name to clients as ordinary KVO-compliant properties. Actually, they’re not so ordinary because they’re inspectable!
Ref #1070, #1147
