This release adds support for the new Go doc comment syntax to gddo.

Some changes in this release include:

- gddo now makes use of go/doc.Package instead of its own doc.Package
  type. This allows us to take advantage of new features in go/doc, such
  as the new go/doc/comment package.
- The way that package documentation is stored in the database has been
  changed. We now store stripped-down Go file ASTs in the database
  instead of a gob-encoded doc.Package.
- The way that VCS autodiscovery information is stored in the database
  has been improved. We now store the raw meta tag values in the
  database.
- The refresh mechanism will always update the module information in the
  database. This avoids problems with out-of-date module information.
- The refresh mechanism will also update VCS information in the
  database. This allows VCS information to be updated without a new
  version release.
- gddo now uses the short-hash of packages with pseudo-versions to
  compute source links. Previously, no links would be generated.
- Templates and assets are now embedded with the embed package.