Add shell for Slave_Driver and for Start_Task.
Also, fix lots of function parameters.
Add Start_Task().
Allows Slave_Driver to make tasks from the integers it receives for its start and end values.
Fix Slave() parameters.
X is not needed in Slave() or in Parallel_Sets_Mixed(), as it is made later.
Fix more parameter problems.
Slave_Driver() and Start_Task() both needed to have A.
Finish Start_Task().