Revert "feat: reset old window when leaving the tree" (#421)

lua/nvim-tree.lua

@@ -194,20 +194,6 @@ function M.reset_highlight()
   renderer.render_hl(view.View.bufnr)
 end
 
-local old_win = nil
-
-function M.save_previous_buf()
-  vim.cmd "wincmd p"
-  old_win = api.nvim_get_current_win()
-  vim.cmd "wincmd p"
-end
-
-function M.set_previous_buf()
-  if old_win then
-    api.nvim_set_current_win(old_win)
-  end
-end
-
 view.setup()
 colors.setup()
 vim.defer_fn(M.on_enter, 1)