Add support for ProPresenter

[croemmich]

Support for PP6 and PP7 should be automatic as the APIs necessary are compatible.

Cue time remaining is available in stagedisplay API: ws://host:port/stagedisplay

Login:

{"pwd":"password","ptl":610,"acn":"ath"}

Listen for:

{
	"acn": "vid",
	"uid": "00000000-0000-0000-0000-000000000000",
	"txt": "--:--:--"
}

End txt values: "--:--:--", "00:00:00", "-00:00:00"

Total time and time elapsed will need to be calculated.

Current cue name is available in remote API: via ws://host:port/remote

Login:

{"action":"authenticate","protocol":"700","password":"password"}

Determine current slide index:

{"action":"presentationSlideIndex"}

Also is broadcast on cue via:

{
  "presentationPath": "0:0",
  "action": "presentationTriggerIndex",
  "slideIndex": 6
}

Grab slideLabel from:

{ "action":"presentationCurrent", "presentationSlideQuality": 25}