title: Change behavior of "control" and "shift" keys in OrbitControls
body: <p>Using a scene with <code>OrbitControls</code> and as far as I can tell by default pressing the <code>ctrl</code> and <code>shift</code> key reverts the left and right mouse movements.
  in my setup left mouse click rotatoes arounds the scene and right mouse clicks move around the 2d plain.
  how can I disable the <code>ctrl</code> and <code>shift</code> key reversing that?</p>
  <p>a hack I found is to edit the controls <code>mouseButtons</code> back when the keys are pressed:</p>
  <pre><code> this.controls.mouseButtons = {
        LEFT: shouldSwitch ? 2 : 0,
        MIDDLE: 1,
        RIGHT: shouldSwitch ? 0 : 2,
      };
  </code></pre>
  <p>using <code>r141</code></p>