Add interface implements annotation

I want use `@interface`,  `@implements {Type}` annotation in my company projects.

these are Google Closure Compiler jsdoc annotations.

i heard that you want add this feature to 3.4.0 but we need this feature 

so i add some codes for this. please check.

thank you.
This will cause problems if, for example, `doc.memberof` is set to a special value like `prototype`.

Use this instead: `if (!hasOwnProp.call(docMap, doc.memberof)) {` (`hasOwnProp` is declared at the top of the module; also, note the space after `if`).