Unique RNG namespace for client-side effects and HUDs. Identifiers for these cannot clash with identifiers that affect the playsim making them completely safe to use in HUD elements. They also won't be saved.
Previously Vel would be reset only if the target was moving. This change
ensures that Vel is always reset, as seems to be the intent of the
oldvel parameter.
- added Marisa Kirisame's CHAN_OVERLAP flag.
- exported S_IsActorPlayingSomething to ZScript.
The sound API change required deprecating A_PlaySound and S_Sound. There are now new variants S_StartSound and A_StartSound which have two distinct parameters for channel and flags.
