title: Regex - delete numbers from string
body: <p>I'd like to find a regex expression to remove numbers from string Only if the char before any number is not alphabetic or is a whitespace. 
  For instance:</p>
  
  <pre><code>_123
  (1234
  .12345
  ?!8
  hi 123
  ?? 1234
  </code></pre>
  
  <p>will be</p>
  
  <pre><code>_
  (
  .
  ?!
  hi
  ??
  </code></pre>
  
  <p>on the other hand:</p>
  
  <pre><code>aaa123
  A1234
  Z_L12345
  ..A8
  aaa a123
  </code></pre>
  
  <p>will be:</p>
  
  <pre><code>aaa123
  A1234
  Z_L12345
  ..A8
  aaa a123
  </code></pre>
  
  <p>Any ideas?</p>
  
  <p>Thank you!</p>