Adding the implementation for the priority with patient preemeption algo...

Here is the implementation for the priority algorithm with patient preemption. I tested it with Lauren's process.txt file, and it worked. 

There are a few things I want to do after this: 
1. I think that the populateInitialQueues, checkWaitingProcesses, getMinimumWaitIndex and passTimeAndCheckWaiting are actually pretty general functions that are likely useful for the other algorithms too. So I'm probably going to move their implementation to the Algorithm.cpp file, to make them usable by other classes. A few changes will have to be made to allow for this though, such as adding a function pointer parameter to some of the functions so that you can pass in the correct sorting predicate to use.