Feature request: More triggers for sound effects

[NathanWeasel]

In particular, I'd like to be able to assign a sound effect to when players try to move heroes into a space but are blocked by a wall (we have a "collision sound" in the default resources folder for exactly that but seemingly no way to use it?), a "play sound" setting on NPCs so they could make squeaks, creaks, jingles, or staircase sounds when touched/stepped on/checked without having to also display a textbox, and possibly also just outright being able to link stairs up/stairs down/teleport type sound effects to doors themselves without having to also place an invisible step NPC on them as well.