title: Filter all types of whitespace in PHP
body: <p>I know that there are many types of space (em space, en space, thin space, non-breaking space, etc), but, all these, that I refered, have HTML entities (at least, PHP's htmlentities() return something like &amp;emsp;.</p>
  
  <p>But, what about those spaces that have no HTML entities?<br>
  Example: [example URL not valid anymore]<br>
  Look at the nickname of this account. It has many " " (spaces) at the front, which are visible for us (this doesn't happen with the &amp;nbsp;).</p>
  
  <p>I tried already filter with regular expressions, using \x escape, filter with str_replace(), with the space as the argument, and no luck at all!</p>
  
  <p>Do you have any suggestion on how to filter ALL  types of whitespace?  </p>