Fixing issue in _setSpeaker
globalising PluginChain like AudioClock
Support for audioMasterIOChanged
Making silence source slightly more useful
Relaxing sample buffer to allow zero-sized buffers
Introducing sampleBufferCopyAndMapChannelsWithOffset
Fixing an issue regarding writing chunks of varying sizes
introducing readInput and writeOutput
Supporting buffer delay compensation and simplifying handling of head skip and tail time

  Fixes #164