[CM] cm3/sndlib with audio and midi file generation

[Bill Schottstaedt]

> How about just doing 
> 
> extern "C" { 
>   <jack-code> 
> } 
>
> instead ? 

I believe audio.c still needs the casts, but I'm no C++ expert  -- the
"extern" business is for the declarations in the header file.
Will check...