These were creating dangerous interdependencies. It is better to do explicit conversions when needed.
As an added plus, this means that zstring.h no longer depends on name.h which was very annoying.
- 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.
