title: QString trim non-whitespace characters from line begin or end
body: <p>Some languages have ltrim(), rtrim() functions with arbitrary characters to trim, however seems QString in Qt does not have anything similar for now. How to implement such with current functionality? Regexp?</p>
  
  <blockquote>
    <p><strong>Note.</strong> Good if Qt team could add add ltrim(), rtrim() methods in QString() like some other languages have:</p>
  </blockquote>
  
  <pre><code>QString ltrim(QByteArray &amp;chars); // trim left
  QString rtrim(QByteArray &amp;chars); // trim right
  </code></pre>
  
  <p>and overloaded </p>
  
  <pre><code>trimmed(QByteArray &amp;chars)
  </code></pre>
  
  <p>to trim arbitrary characters, not only whitespaces. Should be very convenient.</p>