Some issues in RTMP dynamic streaming

[jeroen]

Two issues related to dynamic streaming:

• Switches are currently issued every time the stream to switch to is not the current stream. That should not be the case: switches should only be issued when there is no transition in progress. Otherwise, transition switches will be queued up (instead of overwritten!) and the stream endlessly continues switching.
• Our bandwidth checker includes a small smoothing function that causes switches to occur very late. Since the NetStream.info.maxBytesPerSecond already smoothes out (more than we want!), we should remove our own smoothing.

[jeroen]

Fixed this in [915]:

• Now, when a transition is in progress, no additional transition is issued.
• We don't smooth out switches, but instead wait one bandwidth check until a switch is actually performed. This allows us to filter out switches based upon a single erroneous bandwidth check.

Also make two additional fixes:

• Removed the Logger.log() references that'd ping when transitions were initiated / completed. For some weird reason this would make the stream stop occasionally on my computer.
• Just like the width is matched with a factor of 0.9 in Model.PlaylistItem, added a match for bandwidth of 1.2. This little overhead seems to make things a lot smoother when a user is hovering around the bitrate of a specific stream.