diff layer/TimeInstantLayer.cpp @ 296:ea37c229a578

* Fix #1757772 tempo, dynamic related plug-ins bug -- make auto-align
  only auto-align if there is a unit involved
* Fix #1755366 text layer bug in retrieved session
* Fix input model selection in plugin parameter dialog (was being ignored)
* Use lighter background than the standard widget one for panes (assuming the
  widget background is light but not white) -- similarly darker if dark
* Fix colour reference counting in loaded session in SingleColourLayer
* Reset overview pane colour when switching dark background on or off