Move to supported plugin

init.vim

@@ -78,6 +78,9 @@ set ignorecase
 set smartcase
 " centralize swap to have backup without clutter
 set directory=$HOME/.var/nvim/swp//
+" and undo
+set undofile
+set undodir=$HOME/.nvim/undodir
 " make pastemode more accessible
 set pastetoggle=<F2>
 " save when moving away

mapping.vim

@@ -1,7 +1,7 @@
 " quickly clear Syntastic info
 nmap <F4> :SyntasticReset<CR>
 " toggle gundo's display
-nmap <F5> :GundoToggle<CR>
+nmap <F5> :UndotreeToggle<CR>
 " quickly toggle a right, vsplit for viewing, navigating whatever structure easy
 " tags/tagbar can figure out for the current buffer
 nmap <F9> :TagbarToggle<CR>

plug.vim

@@ -19,7 +19,7 @@ Plug 'tpope/vim-fugitive'
 Plug 'tpope/vim-rhubarb'
 Plug 'mhinz/vim-signify'
 " visualize vim's undo tree
-Plug 'sjl/gundo.vim'
+Plug 'mbbill/undotree'
 " better support for JS
 Plug 'pangloss/vim-javascript'
 " find, complete, etc. on steroids