fix(dirchange): do not change dir when switching windows

- Avoid changing dir when switching windows, except when
changing tabpage.
- Load nvim-tree with passed directory when opening with `nvim DIR`

Fixes #858 #720

lua/nvim-tree.lua

@@ -225,7 +225,7 @@ function M.on_enter(opts)
     M.hijack_current_window()
   end
 
-  lib.init(should_open)
+  lib.init(should_open, lib.Tree.cwd)
 end
 
 local function is_file_readable(fname)