RFR: 8164408: Add module support for @see, @link and @linkplain javadoc tags.

[Hannes Wallnoefer]

Please review:

JBS: https://bugs.openjdk.java.net/browse/JDK-8164408
Webrev: http://cr.openjdk.java.net/~hannesw/8164408/webrev.00/

In the process of adding module support to DocCommentParser I switched the code to using ReferenceParser (both classes contained almost identical code to parse doc comment references, with the only difference being the type of the thrown exception).

An reference like `foo.bar` that would normally resolve to a type or package will result in a link to a module if no type or package exists with that name. If a type or package with the same name exists, a link to the module can be obtained by appending a slash, e.g. `foo.bar/`.

If that behaviour is acceptable I’ll update the CSR at https://bugs.openjdk.java.net/browse/JDK-8191355 accordingly.

Thanks,
Hannes