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.
Ran this through `./ios/docs/install_docs.sh` to double-check things.
* Less-specific initializers above more-specific per Apple convention.
* Shores up `accessToken` docs as property, not a method.
* Edited comments for consistency and/or to keep them out of the docs.
`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
