livoxGen1: Add StimBuffs to PcloudStimProd

* PcloudStimulusProducer now has member sh_ptr<StimulusBuffer>s.
* StimulusProducer now has a vector<sh_ptr<StimulusBuffer>s.

Created new stimbuff-type-specific
Pcloud[Xyz|I|Ambience]StimulusBuffer classes for representing each
stim feature exposed by livoxGen1's PcloudStimulusProducer.

include/user/stimulusProducer.h

@@ -19,6 +19,9 @@
 namespace smo {
 namespace stim_buff {
 
+// Forward declaration
+class StimulusBuffer;
+
 /**
  * StimulusProducer manages a collection of stimulus frames with simultaneity stamps.
  *
@@ -66,6 +69,9 @@ public:
 	void allowNextStimulusFrame()
 		{ frameAssemblyRateLimiter.release(); }
 
+	std::shared_ptr<StimulusBuffer> getAttachedStimulusBuffer(
+		const std::shared_ptr<device::DeviceAttachmentSpec>& spec) const;
+
 protected:
 	SpinLock frameAssemblyRateLimiter;
 
@@ -82,6 +88,7 @@ private:
 
 public:
 	std::shared_ptr<device::DeviceAttachmentSpec> deviceAttachmentSpec;
+	std::vector<std::shared_ptr<StimulusBuffer>> attachedStimulusBuffers;
 
 private:
 	boost::asio::io_service& ioService;