0.84.0

• erepo: cache all read only external repos by hexsha (#3286) @Suor
• GDrive improvements and code cleanup (#3294) @shcheklein
• repro: fix bug in _get_active_graph (#3301) @efiop
• diff: use rev instead of ref (#3299) @efiop
• repo: raise exception if root_dir is not a directory path (#3295) @skshetry
• get/import: they don't work with any DVC project, only DVC repos (as well as Git repos) (#3277) @jorgeorpinel
• add: auto convert absolute_path => relative (#2975) @casperdcl