A daemon manager allows for a layer on top of Java threads to determine
if there are any threads open that are actually doing any processing.
This allows for a thread to wait for all spinoff threads before exiting, whether
or not those threads are daemon threads or not. All the methods in this class
Sets a thread to "daemon" mode, meaning it is currently
active. Null may be sent, in which case a simple count is kept,
but otherwise isn't added to the active threads list. You should
always put a deactivateThread call for every activateThread call.