Simple debug for join, my first app

There is a 'continue' script for the command handler, it is just like "quit" but with a different exit code. When I debug script, I leave a continue after the first join. Then my return code tells the app to call console_loop. I can interrogate the stable state of the machine. When done, I enter "continue" and then script continues processing where it left off. I can only debug between joins.

 I could define the debug mode, and the join operation will have one more test in the loop.  At the bottom of the join loop it is perfectly reasonable, or should be, to call the console_loop(), and check the return for an abort or continue.

 Debugging a stack of joins will be easier than we assume, especially given the native MEM format used, MEM almost always has the intermediate results, and can be examined intelligently.