- Removes nullability shims for Xcode 6.
- Removes MGLTypes.h from files where it was only being used for
nullability support.
- Accepts that `NS_SWIFT_NAME` is not fully supported by Xcode 7.2 and
lower.
- Adds documentation about Xcode 7.3 requirement.
- Makes the use of apostrophes in the iOS SDK documentation consistent by converting “dumb” `'` into smart `’`.
- Adds ticks around class/property names/values.
- Breaks lines at 80 characters.