Dbg:Add CallableTracer for callables post()ed to boost.asio

This class and its macro allow us to trace the invocation of
callbacks as they're invoked by Boost.asio.

smocore/include/opts.h

@@ -11,7 +11,8 @@
 class OptionParser
 {
 public:
-    OptionParser() : verbose(false), printUsage(false) {}
+    OptionParser() : verbose(false), printUsage(false), traceCallables(false)
+	{}
     ~OptionParser() = default;
 
     void parseArguments(int argc, char *argv[], char **envp);
@@ -38,7 +39,7 @@ public:
     std::vector<std::string> senseApiLibs;
     std::string dapSpecs;
     std::vector<std::string> dapSpecFiles;
-    bool verbose, printUsage;
+    bool verbose, printUsage, traceCallables;
 
     static struct option longOptions[];
 };