Decoder modularization - step 1

[Henri Fallon]

On my way for a total wor^H^H^H module domination, I already have
switched the mpeg audio, ac3_spdif and lpcm decoders to modules.

you can find a tar.gz here :
http://www.via.ecp.fr/~henri/videolan/vlc-henri-20011015-02.tar.gz

I'd like to commit this first part on thursday or friday, when the
warnings are repaired (tomorow hopefully). If you have anything to say
about this, feel free (notice it's only a first step).

Next I'll do the Mpeg Video Decoder, which should keep me busy up to 2
weeks, then, when reno has finished with the ac3_decoder, I'll move the
ac3_decoder.

After that, I'll migrate adec_thread_t and vdec_thread_t to a unique
dec_thread_t, and maybe eventually, to nothing at all (Meuuh and I spoke
for a while, we could use only the decoder_config as a common structure
for all decoders ).

Estimated time of Achievement : no idea, probably a month and a half
or so. As I don't really know where I'm going, feel free to send any
reflexion/comment.

-- 
henri