Changes to audio rules

Due to popular demand we have decided to amend our rules as they relate to (main) audio streams in remuxes and internal 720p encodes. It's all spelled out in the rules, but the major changes are this:

- Multichannel audio for new remuxes must remain largely untouched, with the following exceptions: Multichannel LPCM must be encoded to DTS-HD MA. TrueHD must have its embedded AC-3 track removed.
- The same rules govern internal audio for UHD encodes.
- For new internal 720p encodes, DTS encoded/extracted from a lossless source is no longer allowed. DTS is just too inefficient.

Existing torrents uploaded under the previous rules may not be trumped for solely these rule changes.