Multichannel output doesn't work with formats other than 5.0/5.1

[dconrad]

The only multichannel formats that ProcessFloats/Process?16BitSignedInts/Process32BitSignedInts interleave correctly are 5.0 and 5.1. This means that 3.1 and 4.0 formats can't be played when the preference for multichannel output is set. Two examples of such audio are  http://samples.mplayerhq.hu/A-codecs/AC3-samples/3.1-buggy/amelie-ac3-3f%2blfe.avi and  http://umbc.edu/~dconrad1/Byousoku_5cm.mov

Attached are a series of patches to simplify and generalize the sample interleaving code to handle these files.

[dconrad]

Use a single templated function to interleave and convert samples

[dconrad]

Move getting the channel count to its own function

[dconrad]

Simplify and generalize interleaving channels

[dconrad]

Don't set a52_flags based on number of channels; we can handle whatever the stream is

[gbooker]

Comments: 0001: Changed comment about float cast to SInt32 because this is standard procedure documented in liba52's docs. It avoids the whole using FP registers to convert to ints. The integers are signed, not unsigned! See the value of kIntPCMOutFormatFlag

0002: Cleaned up the function (yeah, it was this way originally, but it wasn't my code).

0003: Channel mapping can be done in a more elegant way. Init the map to {0, 1, 2, 3, 4, 5} and the rear channels are always correct. Then, just need to layout the front and LFE channels.

0004: Need to check for mono as well. Also, the channel count *must* match, so check for that.

Committed in changeset 60