Boss Jukebox

## v1.53
- Added a delay before the victory sound plays after a kill (default 1
  second), so it doesn't overlap with WoW's own built-in "boss
  defeated" sound effect. Configurable via the new `victoryDelay`
  SavedVariable (seconds) if 1 second isn't quite right -- not yet
  exposed as its own control in the options panel, so change it by
  editing the default in Core.lua for now if needed.