Reworked the audio resampler.

Reworked the audio resampler.

Original commit message from CVS:
Reworked the audio resampler.
Added first frames skipping to the mp3 and ac3 parser (this allows you to
skip a number of frames before pushing them).
Removed wrong mmx code from the encoder.
Added Macroblocks per slice to the encoder.
added bilinear and bicubic interpolation to the videoscaler.
Added a MPEG1 multiplexer (no SCR or mux rate calculations yet)
Added some options (framerate to the encoder/decoder)