title: Dictionary both case sensitive and insensitive
body: <p>I need a data structure like <code>Dictionary&lt;string,T&gt;</code> where I could do both case sensitive and insensitive searchs.</p>
  
  <p>I am looking to improve the O(n) time that I can get with a <code>List&lt;Tuple&lt;string,T&gt;&gt;</code> by iterating with foreach with a case sensitive or insensitive <code>StringComparer</code>. </p>
  
  <p>This is for a library where I want the end user to select case sensitivity on the <strong>Search</strong> method call. (otherwise I could create a different Dictionary with sensitivity on/off in the class constructor)</p>
  
  <p>Any ideas?</p>