The only thread function: Starts a new thread named "name" with priority "prio" that will begin its execution in the function "thread()". The "arg" argument will be passed as an argument to the thread() function. The stack size to used for this thread is the "stacksize" parameter. The id of the new thread is returned. Both the id and the priority are system dependent. ATTENTION: although this function returns a value, it MUST NOT FAIL (ports have to assert this!)