sound support functions :
-------------------------

Checked/changed functions:

(copied from lsdldoom)
s_sound.c
s_sound.h
sounds.c
sounds.h
l_sound_sdl.c
l_sound_sdl.h   (from lsdldoom i_sound.h)

Non-sound related Changed functions, from lsdldoom (may introduce errors/crash)
  w_wad.c :
  W_CacheLumpNum


to test :
use Z_Malloc instead of Z_Calloc
     s_sound.c : S_Init()
    (channel_t *) Z_Malloc(numChannels*sizeof(channel_t), PU_STATIC, 0);
    
    
    
SDLMixer use :
---------------------------------------------

Mix_Pause
  I_StartSound  - l_sound_sdl.c
  I_InitSound   - l_sound_sdl.c

Mix_Resume
  I_StartSound  - l_sound_sdl.c

Mix_PlayChannel * (done - PlaySampleAtChannel)
  I_StartSound  - l_sound_sdl.c

Mix_Playing * (done - IsPlayingAtChannel)
  I_StartSound      - l_sound_sdl.c
  I_SoundIsPlaying  - l_sound_sdl.c  
  
Mix_HaltChannel * (done - StopSampleAtChannel)
  I_StartSound  - l_sound_sdl.c
  I_StopSound   - l_sound_sdl.c  
  
Mix_VolumeChunk * later (volume;		Per-sample volume, 0-128 )    TBD done integrated at Mix_PlayChannel...
  I_StartSound  - l_sound_sdl.c
  
Mix_SetPanning  * later 
  I_StartSound  - l_sound_sdl.c

Mix_OpenAudio
  I_InitSound   - l_sound_sdl.c

Mix_QuickLoad_RAW *
  I_InitSound   - l_sound_sdl.c

Mix_AllocateChannels
  I_SetChannels - l_sound_sdl.c


TBD:
---
Strafe using right analog stick
fixing NTSC sound
Support for OGG/MOD playing during gameplay
Support for ADPCM streaming during gameplay