Added process priority control. Available when jobs are started and persists through all the jobs in the queue. Defaults to Idle every time a job or set of jobs are started.
Fixed a bug. It's possible the creation of the .State file may fail due to the use of an enumerated type. I changed it to use an int since it can be cast easily and works fine.
Added exception handling in the SaveToFile() method so if a problem occurs we'll be made aware of it in the future.
Fixed the issue where selecting the priority before the encoder actually starts (that small delay between hitting Start and, for example, aften starts) would not affect the priority.
