Parse Javadoc {@link ...} for cross-refs correctly.

Parse Javadoc {@link ...} for cross-refs correctly.

Enable the use of standard Javadoc {@link object text} syntax to
create cross-references to other parts of Android documentation.

- For HTML, link to Android developer docs page
- For Javadoc, identity transform.

Also do a pass through the metadata to add @link where appropriate,
and remove a few outdated references.

Bug: 20085848
Change-Id: I89d77705f8a5f217d1005a7230827d830e96fce8