title: Vim: do not move window content when opening preview / quickfix
body: <p>When splitting Vim window horizontally, contents of the "old" window are scrolled so as to preserve relative cursor line position. This happens even for small "helper" buffers, like quickfix or preview window.</p>
  
  <p>The text movement caused by this becomes annoying when a split is repeatedly opened and closed - e.g. preview window used by completion plugin. Is it possible to disable this feature, and don't scroll old window when splitting (unless it's necessary to keep cursor line visible)?</p>
  
  <p>Example - current behavior:</p>
  
  <pre><code>+--------------+              +--------------+
  | a            |              | b            |
  | b            |    copen     | c  (cursor)  |
  | c  (cursor)  |     --&gt;      | d            |
  | d            |              +--------------+
  | e            |              |  (preview)   |
  +--------------+              +--------------+
  </code></pre>
  
  <p>Desired behavior:</p>
  
  <pre><code>+--------------+              +--------------+
  | a            |              | a            |
  | b            |    copen     | b            |
  | c  (cursor)  |     --&gt;      | c  (cursor)  |
  | d            |              +--------------+
  | e            |              |  (preview)   |
  +--------------+              +--------------+
  </code></pre>