message: feat(viewer): adds method to customise camera max polar angle at runtime
  this controls wether the camera can look from down upwards - by default this is off, but now it can
  be easily re-enabled.
diff: @@ -147,6 +147,15 @@ export default class InteractionHandler {
  this.viewer.camera.updateProjectionMatrix()
  }
  + /**
  + * Allows camera to go "underneath" or not. By default, this function will set
  + * the max polar angle to Pi, allowing the camera to look from down upwards.
  + * @param {[type]} angle [description]
  + */
  + setMaxPolarAngle( angle = Math.PI ) {
  + this.viewer.controls.maxPolarAngle = angle
  + }
  +
  rotateCamera( azimuthAngle = 0.261799, polarAngle = 0, transition = true ) {
  this.viewer.controls.rotate( azimuthAngle, polarAngle, transition )
  }
  