v1.2.0

It gets 3 months to be released but there is a lot of work to do.
Still it should be released some day and better sooner than later.

- New rules: checkParamExistence and requireReturnDescription (thanks to Jon Robson and @weekens).
- enforceExistence rule: a couple of change (thanks to Sergey Zarouski and Matt Votsikas).
- New tags in jsdoc3 set: interface, inheritdoc, implements.
- A couple of bug fixes by reports and pull requests.
- And so on...

Thank you for bug reports and contribution!