Adds a new step_trigger, "sound_effect", acts as a mapper friendly wrapper for playing sound effects
Adds a new step_trigger variable, "mobs_only", like affects_ghosts this is a boolean for allowing/denying atom/movables from triggering step_triggers
playsound_local() is now a /atom proc, all mob specific requirements have been moved to an override
Fixes some backwards logic
Clientless atoms don't get sound
Atoms don't have clients, Revert of previous commit
Merge pull request #6330 from RemieRichards/MapperFriendlySoundTrigger

Simple sound effect map object