Added an 'inTimeStamp' parameter to AEMixerBufferSource
Added some asserts to AEMixerBuffer to ensure timestamp validity
Altered AEMixerBuffer to allow empty timestamps
Updated documentation to mention ABAudiobusAudioUnitWrapper
AEBlockScheduler.m: make explicit cast from long to UInt32
Merge pull request #94 from arielelkin/AEBlockChannel_make_explicit_cast

AEBlockScheduler.m: make explicit cast from long to UInt32
Added "floatFormatChannelsPerFrame" property to AEFloatConverter
Merge branch 'refs/heads/master' into audiobus2