title: update cscope db from vim
body: <p>I use cscope with vim.
  When doing large edits for several files, cscope will report old line numbers for changed files. 
  How can I rebuild cscope db from vim without losing </p>
  
  <ul>
  <li>opened tabs/windowses in vim</li>
  <li>connection with cscope engine</li>
  </ul>
  
  <p>Thanks</p>