- add more examples; update examples

- now runs in the Xcode 6 b6 playground
- add MARK sections
- more examples

- add custom operator example
- add landmark notes
- add more examples; add book link

- add link to official Swift book from Apple
- add examples of access control and structures
- update protocols
- fix merge swift conflict

- Merge master
Merge pull request #732 from cbess/master

[swift/en] - add more examples; update examples