Update for new(?) iheart API

 A week or so ago, iHeartRadio incompatibly changed the API this script had
 been depending on. While not all functionality has been restored (most notably
 the capability to select stream types no longer exists, or I haven't found it
 yet), deep-packet inspection of various official iHeartRadio apps' traffic has
 provided a new mechanism to get stream URLs... for now. As I study official
 apps more, further information may be obtained.