Merge branch 'gb/gitweb-remote-heads'

* gb/gitweb-remote-heads: git instaweb: enable remote_heads gitweb: group remote heads by remote gitweb: provide a routine to display (sub)sections gitweb: refactor repository URL printing gitweb: remotes view for a single remote gitweb: allow action specialization in page header gitweb: nagivation menu for tags, heads and remotes gitweb: separate heads and remotes lists gitweb: git_get_heads_list accepts an optional list of refs gitweb: introduce remote_heads feature gitweb: use fullname as hash_base in heads link