Frame pool

[gavv]

Make frame pooled and holding reference to a buffer, also pooled.

This will allow to create queues/ring buffers of frames, reuse existing buffers (e.g. attach buffer from packet directly to a frame), and reuse existing frames (e.g. return same frame twice).

This is also needed to be able to return frame of different size than requested and thus implement partial reads (#615).

• [x] rework Buffer:
  • make Buffer non-template (always bytes)
  • make BufferFactory non-template
  • keep Slice template
• [x] rework factories
  • PacketFactory: new_packet_buffer(), new_packet()
  • FrameFactory: new_byte_buffer(), new_raw_buffer()
  • remove BufferFactory
• [x] rework Frame
  • Slice<uint8_t> buffer()
  • void set_buffer(Slice<uint8_t>)
• [x] pooled frames
  • FramePtr
  • FrameFactory: allocate_frame(), reallocate_frame()
• [x] IFrameWriter:
  • StatusCode write(Frame&)
• [x] IFrameReader:
  • StatusCode read(Frame&, packet::stream_timestamp_t duration)
• [x] Update roc_audio:
  • [x] Mixer
  • [x] Fanout
  • [x] ResamplerReader
  • [x] ResamplerWriter
  • [x] ChannelMapperReader
  • [x] ChannelMapperWriter
  • [x] PcmMapperReader
  • [x] PcmMapperWriter
  • [x] ProfilingReader
  • [x] ProfilingWriter
  • [x] Watchdog
  • [x] NullWriter
  • [x] Depacketizer
  • [x] Packetizer
  • [x] LatencyMonitor
  • [x] FeedbackMonitor
• [x] Update roc_sndio:
  • [x] IDevice
  • [x] IBackend
  • [x] BackendDispatcher
  • [x] Pump
  • [x] WavBackend
  • [x] SoxBackend
  • [x] SndfileBackend
  • [x] PulseaudioBackend
• [x] Update roc_pipeline:
  • [x] PipelineLoop
  • [x] ReceiverLoop
  • [x] ReceiverSource
  • [x] SenderLoop
  • [x] SenderSink
  • [x] TranscoderSource
  • [x] TranscoderSink
• [x] Update roc_node
  • [x] Context
  • [x] Sender
  • [x] SenderEncoder
  • [x] Receiver
  • [x] ReceiverDecoder
• [x] Update public_api:
  • [x] roc_sender
  • [x] roc_sender_encoder
  • [x] roc_receiver
  • [x] roc_receiver_decoder
• [x] Update tools:
  • [x] roc_send
  • [x] roc_recv
  • [x] roc_copy
• [x] Update tests
  • [x] roc_audio
  • [x] roc_sndio
  • [x] roc_pipeline
  • [x] roc_node
  • [x] public_api
• [x] Remove set_duration() hacks:
  • [x] PipelineLoop
  • [x] Mixer