Async: new hierachy; manages reply posting and unlocking

Async: Use new [Non]PostedAsyncCont and callOriginalCb

This new hierarchy of classes gives us a central mechanism for
managing both reply-posting and lockSpec unlocking.

* callOriginalCb: Now uses a modern C++ variadic template design
  enabling it to handle both direct calling and std::bind()
  re-binding of an arbitrary number of arguments from the caller.

This enables us to mostly eliminate the repeated, bespoke
definitions of callOriginalCb littered throughout the codebase.

We've also propagated these changes throughout the codebase in
this patch.

smocore/body/body.cpp

@@ -16,27 +16,16 @@ Body::Body(Mind &parent, const std::shared_ptr<ComponentThread> &thread)
 }
 
 class Body::InitializeReq
-:	public AsynchronousContinuation<bodyLifetimeMgmtOpCbFn>,
-	public ContinuationTarget
+:	public PostedAsynchronousContinuation<bodyLifetimeMgmtOpCbFn>
 {
 public:
 	InitializeReq(
 		Mind &parent, const std::shared_ptr<ComponentThread> &caller,
 		bodyLifetimeMgmtOpCbFn callback)
-	:	AsynchronousContinuation<bodyLifetimeMgmtOpCbFn>(callback),
-		ContinuationTarget(caller),
+	:	PostedAsynchronousContinuation<bodyLifetimeMgmtOpCbFn>(caller, callback),
 	parent(parent)
 	{}
 
-	void callOriginalCbFn(bool success)
-	{
-		if (originalCbFn)
-		{
-			caller->getIoService().post(
-				std::bind(originalCbFn, success));
-		}
-	}
-
 private:
 	Mind &parent;
 
@@ -104,7 +93,7 @@ public:
 			<< results.nSucceeded << " of " << results.nTotal
 			<< " sense devices." << "\n";
 
-		callOriginalCbFn(results.nSucceeded > 0);
+		callOriginalCb(results.nSucceeded > 0);
 	}
 };
 
@@ -148,7 +137,7 @@ public:
 
 		std::cout << "Mrntt: About to unload all sense api libs." << "\n";
 		sense_api::SenseApiManager::getInstance().unloadAllSenseApiLibs();
-		callOriginalCbFn(results.nSucceeded == results.nTotal);
+		callOriginalCb(results.nSucceeded == results.nTotal);
 	}
 };