StimBuff: Use a single StagingBuffer for all StimFrames

We now allocate all the stimFrames for a StimBuffer using a
single StagingBuffer. This gives us all the benefits we're
looking for (pinning, alignment, etc).

include/user/stimulusFrame.h

@@ -2,7 +2,7 @@
 #define _ATTACHMENT_SUPPORT_STIMULUS_FRAME_H
 
 #include <cstdint>
-#include <user/stagingBuffer.h>
+#include <user/frameAssemblyDesc.h>
 #include <user/sequenceLock.h>
 
 namespace smo {
@@ -69,12 +69,8 @@ public:
 	 */
 	StimulusFrame() = default;
 
-	StimulusFrame(
-		const StagingBuffer::IOEngineConstraints& inputEngineConstraints,
-		const StagingBuffer::IOEngineConstraints& outputEngineConstraints,
-		size_t nSlots)
-	: stagingBuffer(
-		inputEngineConstraints, outputEngineConstraints, nSlots)
+	StimulusFrame(const FrameAssemblyDesc::SlotDesc& slotDesc_)
+	: slotDesc(slotDesc_)
 	{}
 
 	~StimulusFrame() = default;
@@ -88,7 +84,7 @@ public:
 public:
 	SequenceLock lock;
 	SimultaneityStamp simultaneityStamp;
-	StagingBuffer stagingBuffer;
+	FrameAssemblyDesc::SlotDesc slotDesc;
 };
 
 } // namespace stim_buff