finesse nerdtree, and don't open it on startup
finesse nerdtree, and don't open it on startup

set nerdtree width to 45%

rm superfluous leading :

to open nerdtree on startup

```vim
" start nerdtree when vim starts with a directory argument
function! s:NERDTreeOnStartDirArg() abort
  if argc() >= 1 && isdirectory(argv()[0]) && !exists('s:std_in')
    silent doautocmd User LoadNERDTree
    execute 'NERDTree' argv()[0]
  endif
endfunction

augroup NERDTreeOnStart
  autocmd!
  autocmd StdinReadPre * let s:std_in=1
  autocmd VimEnter * call <SID>NERDTreeOnStartDirArg()
augroup END
```

atweiden/macfiles