Students T-Test

Added functions for Students T-Test one sample and independant sets and a function to convert a t-value to a p-value. Not sure about the naming, if you would like me to change the function names and resubmit requrest, let me know. I have tests, I will add examples next week and I would like to add dependant sets after that.
Oh, I understand what this is now. It seems to me like the actual probability computation should come from a T distribution (which would exist in stat/dist). Then, this could maybe transform into a helper function using the results from TTest and a TDistribution.