-add a function prototype for add_job_to_queue()
-adjusted change_job_priority() to add the job before the jobs of its same priority if it has already been started, but add it at after the jobs of its same priority if it hasn't been started

-adjusted parameters of functions so that the pointer to the head function has to be passed to them
-updated faulty notes
-edited main() so that it set the priority of the head distrenjob to zero
-changed queue() to prepare_distrenjob()
-deleted global \"struc distrenjob *head\" variable because it is created in main()

created function \"change_job_priority\" and \"remove_job\" (this remove_job function recieves a job number and returns structure distrenjob, it was made to assist the change_job_priority function)

I also fixed an error where add_job_to_queue wasn't updating its prev_job pointer, which would of resulted in the loss of jobs between head and where the new job is inserted.