Excalibur v0.18.0

Breaking Changes

• Sound.setVolume() replaced with Sound.volume
• Sound.setLoop() replaced with Sound.loop

Added

• Add Scene.isActorInDrawTree method to determine if an actor is in the scene's draw tree.

Fixed

• Fixed missing exitviewport/enterviewport events on Actors.on/once/off signatures (#978)
• Fix issue where Actors would not be properly added to a scene if they were removed from that scene during the same frame (#979)