another crash fix, plus build path introspection
another crash fix, plus build path introspection

* Get reference counts right on result object when invoking performance callback for real this time.

* Make CTableBuildPath return the current build path if no dir is specified.  Why didn't this always work that way.

flightaware/speedtables,flightaware/speedtables,flightaware/speedtables,flightaware/speedtables