Experimental support for synchronizing output of multiple consumers. For example...

Experimental support for synchronizing output of multiple consumers. For example using a Decklink Quad with one consumer for fill and one for key. Place the consumer elements in casparcg.config within a <synchronizing /> element. For example:

<consumers>
  <synchronizing>
    <decklink>
      <device>1</device>
      <embedded-audio>true</embedded-audio>
    </decklink>
    <decklink>
      <device>2</device>
      <key-only>true</key-only>
    </decklink>
  </synchronizing>
</consumers>

Also added new INFO command showing some information about delays (producer - mixer - consumer):

INFO 1 DELAY
INFO 1-10 DELAY