simultaneous commands collide and fail

[scruss]

Note Limitations:

In order to keep the code simple and to avoid implementing a server model, commands sent simultaneously to the gateway have undefined results: one command may succeed, but more likely, all simultaneous commands may fail. This can be a confusing issue when using ihsctrl from cron, as jobs triggered from separate crontab lines may collide and fail.

Adding concurrent access/queuing would make the system too complicated for me to understand.