Progress: controller program thread support.

Progress: controller program thread support.

This is the initial pass at getting the thread support implemented.
There were several necessary changes in how the cache is defined and used.

This is very much incomplete.
All of the printf functions after a certain point need to be protected by a print mutex.

I need to figure out if and how to handle child processes from an execv() call from inside a thread.
Ideally it needs to gracefully exit and cleanup resources in the child process.

Just like with the child process and execv() the signal/interrupt handling needs to be handled in a way that gracefully exits as appropriate.
Prior to adding thread support, I added signal support and tested that it works.
These interrupt signals work but have not been tested or reviewed now that the threading is added.

A quick execution of this code shows that there are invalid reads (and therefore segfaults).
I need to pick up here and make sure all of the resources are being properly managed.