Changed Audiobus input support to use Audiobus's live mode for simplicity

Previously, AEAudioController's audiobusInputPort was used to receive audio from Audiobus via the "lossless" stream mode. This ensured audio received was identical to audio sent from the Audiobus source, but at the cost of increased latency and unpredictable audio receive intervals, which increased the complexity of receiving apps due to the necessity of dealing with buffer under runs by using a separate "live" stream for monitoring (using AEPlaythroughBuffer or manually).

This change causes AEAudioController to only use Audiobus' "live" mode for input, removing the necessity of dealing with the particulars of "lossless" mode with little tradeoff, as live mode yields excellent results.
AEMixerBuffer: Don't set the mDataByteSize values of buffer lists on return
AEMixerBuffer and AEFloatConverter: Preserve AudioBufferList mDataByteSize fields on return
Allowed time stretching filters by keeping per-channel timeStamps.
Merge pull request #50 from psobot/timestretch_fix

Allowed time stretching filters by keeping per-channel timeStamps.
Changed AEAudioFileWriter to use software encoder for M4A recordings, since hardware encoders are not allowed to be used simulatenously with I/O audio units
Merge pull request #52 from nilknarfuw/master

Changed AEAudioFileWriter to use software encoder for M4A recordings, since hardware encoders are not allowed to be used simulatenously with I/O audio units
Update channel producer hostTime correctly

This fixes a problem introduced in SHA 3bcb6f1, and closes #53
Implemented master output volume control
add a startLoopBlock, A block to be called when in loop playback the loop restarts/begins again
Addressed an iOS 7-related crash
Remove setting the playhead in startLoop Block

Remove setting the playhead in the main-thread notification method, cause it doubles with Line 160 and may create a jitter & click on loop boundary.
Merge pull request #55 from ploenne/master

Add a startLoopBlock on Class AEAudioFilePlayer
Minor tweaks to prior commit
Added workaround for iOS 7 audio session interruption bug
Added missing static keyword for consts
Workaround for buggy audio hardware latency reporting on iOS 7
Updated AEPlaythroughChannel to provide support for ABInputPort's new muteLiveAudioInputWhenConnectedToSelf
Addressed some trivial Xcode 5 compiler warnings
Avoid infinite recovery loop with unrecoverable system errors