Merge branch 'jn/web'

* jn/web:
  gitweb: Finish restoring "blob" links in git_difftree_body
  gitweb: Refactor feed generation, make output prettier, add Atom feed
  gitweb: Add an option to href() to return full URL
  gitweb: New improved formatting of chunk header in diff
  gitweb: Default to $hash_base or HEAD for $hash in "commit" and "commitdiff"
  gitweb: Buffer diff header to deal with split patches + git_patchset_body refactoring
  gitweb: Protect against possible warning in git_commitdiff