Misc bug fixes

- There was a bug where the decoder resampler was not properly initialized
when fs_kHz == API_fs_kHz. In that case the resampler would continue to
upsample, and the output was corrupt.

- The delay value in the decoder was taken from the state before it was
potentially updated. This caused the decoder to apply the new dalay value one
frame late

- The encoder and decoder states are now updated more consistently, when
the sampling rate changes (pesq liked these changes)

- Properly resetting the side channel encoder and decoder for the first
frame with side coding active again

- Faster updating the "ratio" value in the LR_to_MS() code for large
prediction values means that for certain extreme/artificial input
signals the output looks better

src/opus_decoder.c

@@ -802,9 +802,7 @@ int opus_decoder_ctl(OpusDecoder *st, int request, ...)
       if (st->prev_mode == MODE_CELT_ONLY)
          celt_decoder_ctl(celt_dec, OPUS_GET_PITCH(value));
       else
-         *value = ((silk_decoder_state*)silk_dec)->indices.signalType == TYPE_VOICED
-         ? ((silk_decoder_state*)silk_dec)->lagPrev*48/((silk_decoder_state*)silk_dec)->fs_kHz
-         : 0;
+         *value = st->DecControl.prevPitchLag;
    }
    break;
    default: