AE: fixes and cleanup

credits to @warped-rudi it turned out that we treated S24NE4 wrong for ALSA and PA. Windows assumes the 24 bits in the upper 3 bytes, ALSA in the lower 3. This fact required a new audio format S24NE4R.

In order to avoid further confusion on where audio conversion is done, this PR removes the CAEConvert class. All conversion, resampling, remapping ins done in CActiveAEResampler.