Fork increment

​I finish the thread program, and it outputs just like the increment.c.
But the program takes a long time to executes. Longer than the increment.c
I think Sweany wanted the outputs to take less time than the increment.c but I'm not sure. 
If you guys want to take a look at it and see if there is any changes I need to make, please feel free to do so.
I put it up on github and attached it to this email. 

Other than that, the two programs are basically finish.
I'll wait until 9pm today for your responses, and then upload it into moodle. 

Ester Lee
Group 20.