Starts a threadpool and runs functions in the pool

NOTE - this is for demonstration only and is not threadsafe. Be warned!

All functions are under the namespace .threads

There is only one function

• async[job;callback] runs the job and returns data to the callback

The parameters are

• job(parselist) parse list of expression to evaluate
• callback(fn[x]) takes in result of job

.threads.async[((*);5;3);{xx::x}] //Result is 15