fugitive.vim 2.3

* Support worktrees.
* Provide API for extensible :Gbrowse support.
* Remove GitHub URL support in favor of rhubarb.vim.
* Provide :Gdelete to delete both file and buffer.
* Provide :Grename to move relative to file's parent directory.
* Split to open file when :Gstatus is only window.
* Provide U in :Gstatus to discard changes.
* Provide additional :Gstatus commit maps.
* Provide d2o and d3o to obtain diff during conflict.
* Support :tab Gcommit.
* Open :Gcommit tab before current.
* Support :Gdiff +cmd.
* Support gf in Git file types.
* Add flagship.vim statusline indicator.
* Use the Neovim terminal emulator for :Git.
* Bug fixes.